ServiceNow OAuth Handler Script Include for processing OAuth Responses from GitHub

OAuthGitHubHandler.js

var OAuthGitHubHandler = Class.create();
OAuthGitHubHandler.prototype = Object.extendsObject(OAuthUtil,  {
	// Override postprocessAccessToken method. GitHub returns a urlencoded
	// body, so we need to break this apart and extract the values. 
	postprocessAccessToken: function(accessTokenResponse) {
		var contentType = accessTokenResponse.getContentType();
		var contentBody = accessTokenResponse.getBody(); 
		var paramMap = accessTokenResponse.getparameters();
		var params = contentBody.split('&'); 
		var parts; 
		
		params.forEach(function(param) {
			parts = param.split('=');
			paramMap.put(parts[0], parts[1]);
		});
		
		// GitHub tokens do not expire, hardcode expiration to something far away
		paramMap.put('expires_in', '365246060'); 
	},
	
	type: 'OAuthGitHubHandler'
});

Can this be extended to add a header? If not then is there a way I can add a header for OAuth call?