Facebook and default screen name

Hi

I was wondering if it is possible to set the screen name used when using facebook connect to register to the website.

At the moment it shows the email address because I have setup the email address to be the same as the login name…

With twitter I found the code:
$sc_screen_name = $_REQUEST[ 'social_connect_screen_name' ];
to set the screen name, but when adding this code (with a few modifications) to the facebook part it wont work.

Could you give me a point in the right direction here? I’m not sure why it wont work.