If a form-based login must be filled out before accessing a site,
the Custom Primer URL can be set to the <FORM ACTION> URL of the
login (fully-qualified), with any form variables (e.g. user/pass)
filled out in the query string. If the <FORM METHOD> must be
POST instead of GET, the URL protocol may be changed to
the pseudo-protocol "http-post". E.g.:
would be submitted using the POST method, with the given
query-string variables sent as the content. Note that the
query-string variables and values should be URL-encoded.
