Documentation
Configuration / SessionAuthenticator.logged_in_key
This option enables you specify what session key to check for if the user is logged in or not. The session value of this key should be set to true if the user is to access the MoxieManager.
$moxieManagerConfig['SessionAuthenticator.logged_in_key'] = "IsLoggedIn";
<add key="SessionAuthenticator.logged_in_key" value="IsLoggedIn" />
In your own application simply set the session variable to the above key, and it should authenticate that user.
$_SESSION["IsLoggedIn"] = true;
Session["IsLoggedIn"] = true;
The SessionAuthenticator will check for that session to validate the user, so in your login page, set and everything should work just fine.