Expanding Facebook Scope from a Force.com Social Application

Friends.page

<apex:page controller="FriendsController">
  <script src="https://connect.facebook.net/en_US/all.js"></script>
  <div id="fb-root"></div>
  <script>
    // Get required permissions from the controller
    var permissions = '{!permissions}';
    var permlist = permissions.split(',');
    var reqperms = '';
  
    FB.init({appId: '{!appId}', xfbml: true, cookie: true});
    
    // We are logged in, but we need getLoginStatus() to get the FB JS
    // lib to pick up the access token
    FB.getLoginStatus(function(response) {
      if (response.status === 'connected') {
        // Check we have the permissions we want
        FB.api('/me/permissions', function (response) {
          for (var i = 0; i < permlist.length; i++) {
              if (! response.data[0][permlist[i]]) {
                  if (reqperms !== '') {
                      reqperms += ',';
                  }
                  reqperms += permlist[i];
              }
          }
          if (reqperms.length > 0) {
            // We need some permissions - ask for them
            FB.login(function(response) {
              if (!response) {
                alert('Error getting permission!');
              } else {
                location.reload(true);
              }
            }, {scope: reqperms});
          }
        });
      } else if (response.status === 'not_authorized') {
        // The user is logged in to Facebook, 
        // but has not authenticated the app
        // We handle this in the controller
      } else {
        // The user isn't logged in to Facebook.
        // We handle this in the controller
      }
    });   
    
    // Pop up a dialog to send a message to another user
    var sendMessage = function(id) {
      FB.ui({
        method: 'send',
        to: id,
        name: 'Authentication Provider Test Portal',
        link: 'https://authtest-developer-edition.na14.force.com/',
        description: 'Come to the cool test portal today!'
      });    
    }; 
  </script>
  <apex:pageMessages/>
  <apex:pageBlock >
    <apex:outputText >Controller says '{!data}'.</apex:outputText>
  </apex:pageBlock>
  <apex:pageBlock title="Facebook Friends in this Portal">
    <apex:pageBlockTable value="{!friendsInPortal}" var="friend">
      <apex:column width="70">
        <apex:outputLink target="_new" value="https://www.facebook.com/{!friend.id}">
          <img src="https://graph.facebook.com/{!friend.id}/picture?type=square"/>
        </apex:outputLink>
      </apex:column>
      <apex:column headerValue="Name" style="vertical-align: middle;">
        <!-- Link to each friend's Facebook page -->
        <apex:outputLink target="_new" value="https://www.facebook.com/{!friend.id}">
          {!friend.name}
        </apex:outputLink>
      </apex:column>
    </apex:pageBlockTable>
  </apex:pageBlock>
  <apex:pageBlock title="All Facebook Friends">
    <apex:pageBlockTable value="{!friends}" var="friend">
      <apex:column width="70">
        <apex:outputLink target="_new" value="https://www.facebook.com/{!friend.id}">
          <img src="https://graph.facebook.com/{!friend.id}/picture?type=square"/>
        </apex:outputLink>
      </apex:column>
      <apex:column width="140" headerValue="Name" style="vertical-align: middle;">
        <!-- Link to each friend's Facebook page -->
        <apex:outputLink target="_new" value="https://www.facebook.com/{!friend.id}">
          {!friend.name}
        </apex:outputLink>
      </apex:column>
      <apex:column style="vertical-align: middle;">
        <!-- Link to each friend's Facebook page -->
        <a href="#" onclick="sendMessage('{!friend.id}'); return false;">
          Invite {!friend.first_name}
        </a>
      </apex:column>
    </apex:pageBlockTable>
  </apex:pageBlock>
</apex:page>

FriendsController.cls

public class FriendsController {
    public List<FacebookUser> friends { get; set; }
    public List<FacebookUser> friendsInPortal { get; set; }    
    public String data { get; set; }
    
    public FriendsController() {
        // Replace the ID in this call with the ID of your auth provider
        String access_token = Auth.AuthToken.getAccessToken('0SOd0000000abcd', 'Facebook');
        
        try {
            // Get friends ID, name, first name via Graph API
            Map<String,String> params = new Map<string,string>{'fields' => 'id,name,first_name'};
            FacebookUsers friendsList = new FacebookUsers(access_token, 'me/friends', params);
            
            friends = friendsList.data;
            
            // Figure out which friends are in the portal
            Map<String,FacebookUser> friendMap = new Map<String,FacebookUser>();
            
            for (FacebookUser fbu : friends) {
                friendMap.put(fbu.id, fbu);
            }
            
            List<User> users = [SELECT Facebook_ID__c FROM User WHERE Facebook_ID__c IN :friendMap.keySet()];
            
            friendsInPortal = new List<FacebookUser>();
            for (User u : users) {
                friendsInPortal.add(friendMap.get(u.Facebook_ID__c));
            }
            
            // Get the authenticated user's profile and see if we can see the fields
            // for which we requested permission
            FacebookUser me = new FacebookUser(access_token, 'me');
            data = 'Religion: ' + ((me.religion != null) ? me.religion : 'null');
            data += ' / ';
            data += 'Hometown: ' + ((me.hometown != null) ? me.hometown.name : 'null');
        } catch (FacebookException fbe) {
            // This can happen if the user revokes permissions for the app
            // while they are in the portal...
            data = '';
            friends = new List<FacebookUser>();
            friendsInPortal = new List<FacebookUser>();
            ApexPages.Message myMsg = new ApexPages.Message(ApexPages.Severity.FATAL,
                'Error accessing Facebook. Please logout of the portal and log back in.');
            ApexPages.addMessage(myMsg);
        }
    }
    
    public String getAppId() {
        // Replace this with your auth provider's consumer key
        return '123456789012345';
    }

    public String getPermissions() {
        // FB permissions for the religion and hometown profile data
        return 'user_religion_politics,user_hometown';
    }    
}

PortalHandler.cls

global class PortalHandler implements Auth.RegistrationHandler{
    global User createUser(Id portalId, Auth.UserData data){ 
        Account a = [SELECT Id FROM account WHERE name='sForce']; 
        Contact c = new Contact();
        c.accountId = a.Id; 
        c.email = data.email; 
        c.firstName = data.firstName; 
        c.lastName = data.lastName; 
        insert(c); 
    
        User u = new User();
        Profile p = [SELECT Id FROM profile WHERE name='High Volume Customer Portal']; 
        
        // Use incoming email for username, since we're creating a portal user
        u.username = data.email; 
        u.email = data.email; 
        u.lastName = data.lastName; 
        u.firstName = data.firstName; 
        u.Facebook_ID__c = data.identifier;
        u.alias = (data.username != null) ? data.username : data.identifier; 
        if (u.alias.length() > 8) {
            u.alias = u.alias.substring(0, 8); 
        }
        u.languagelocalekey = UserInfo.getLocale();
        u.localesidkey = UserInfo.getLocale();
        u.emailEncodingKey = 'UTF-8'; 
        u.timeZoneSidKey = 'America/Los_Angeles'; 
        u.profileId = p.Id; 
        u.contactId = c.Id; 
        
        System.debug('Returning new user record for '+data.username); 
          
        return u; 
    }

    global void updateUser(Id userId, Id portalId, Auth.UserData data){ 
        User u = new User(id=userId); 
        
        u.email = data.email; 
        u.lastName = data.lastName; 
        u.firstName = data.firstName; 
        u.Facebook_ID__c = data.identifier;

        System.debug('Updating user record for '+data.username); 
          
        update(u); 
    }
}

Is it possible to use String access_token = Auth.AuthToken.getAccessToken('0SOd0000000abcd', 'Facebook'); in the Portal Handler.cls under createUser method?

I tried to access token in the AuthRegistration Handler class and it is returning null value (and as a result OAuth Exception).