How to pass fb_sig_session_key to Facebook Connect?

Question

Hi,

I want to get a "permanent" session, i.e. in my app i ask the user for permission for offline_access

FB.Connect.showPermissionDialog("offline_access");

In the POST url I get the fb_sig_session_key, and I understand that all i need to do now is to use this fb_sig_session_key, and the user would not need to login with user/password.

The info that is missing is HOW do I use the fb_sig_session_key?

I would suspect that I would pass the key to any of the init functions, e.g. to the init method or the apiClient (see below which functions i mean).

But none of those functions seems to be the target. Can someone help me out here? I guess that is all that is missing for me to get a working example on how to do offline_accesss, but i cannot find out how to do it.

var channel_path = 'xd_receiver.htm'; 
 FB_RequireFeatures(["Api"], function(){
 // Create an ApiClient object, passing app's API key and
 // a site relative URL to xd_receiver.htm
 FB.Facebook.init(api_key, channel_path);
 var api = FB.Facebook.apiClient;

 // require user to login
 api.requireLogin(function(exception){
...