Of course it is. However you will not only need to change the template but the actual script file, to check for the information you need. There will also need to be some alterations/additions in the language files to display error messages when the information you want to store is not filled in (i.e. Address not filled in, or Address cannot be more than 200 characters, etc.)
On the top of my head you will need the newuser.php, newuser.tmpl and adduser.php files
Warm regards
Nikos
