[Dark Odin]

For Template driven:

PHP Code:

if($bbuserinfo['userid'] != 0) {
          eval("\$reg_ucp = \"".gettemplate("unregged")."\";");
        }else{
eval("\$reg_ucp = \"".gettemplate("regged")."\";");
} 


Just create the templates unregged and place your register button code or link, and put your user cp link code in regged template.

Not sure if this works, but it looks like it should.