http://www.zen-cart.com/forum/showth...ghlight=fields

Try that thread... worked for me...

I added 3 fields to login. I did try toying wit validating one of the fields..
I was asking for another birthday... but that seemed to really complicate things and I'm not concerned with the client entering it in a different format or making a typo.
I just kept it as a text filed.... It worked great...

Hope that helps.