Subclass AWSQueryConnection and define a _required_auth_capability(self) function returns a list which includes the unique capability of the desired auth handler plugin.

gistfile1.py

class AWISQueryConnection(AWSQueryConnection):
    def _required_auth_capability(self):
        return ['sign-v2']

def alexa_rank(url):
    conn = AWISQueryConnection(
            aws_access_key_id=config.aws['key'],
            aws_secret_access_key=config.aws['secret'],
            host='awis.amazonaws.com',
            is_secure=False,
            debug=1)

    conn.APIVersion = '2005-07-11'
    conn.SignatureVersion = '2'
    response = conn.make_request('UrlInfo', params={
        'Url': url,
        'ResponseGroup': 'ContactInfo,Rank,LinksInCount'
    })

    res = response.read()

    dom = xml.dom.minidom.parseString(res)

    od = {}
    od['links'] = self._get_text(dom, "aws:LinksInCount")
    od['rank'] = self._get_text(dom, "aws:Rank")
    od['phone'] = self._get_text(dom, "aws:PhoneNumber")
    od['email'] = self._get_text(dom, "aws:Email")
    od['rank'] = self._get_text(dom, "aws:Rank")
    od['name'] = self._get_text(dom, "aws:OwnerName")
    od['street'] = self._get_text(dom, "aws:Street")
    od['city'] = self._get_text(dom, "aws:City")
    od['state'] = self._get_text(dom, "aws:State")
    od['zip'] = self._get_text(dom, "aws:PostalCode")
    od['country'] = self._get_text(dom, "aws:Country")

    if od['rank'] is None:
        return 0

    return int(od['rank'])