Many existing sites use a client module (livewhale/client/module/secure_submissions or similar) for this functionality, but as of LiveWhale 3.0+ you can do the same with this simple flag in your client.config.php file:

$_LW->CONFIG['SUBMISSIONS_REQUIRE_SSO']=true; // require SSO login to access the submission form

This will affect the submission page or any other page containing <widget type=”submissions”/>