Neha,
Just a note: we recommend creating a separate enrollment form using the programming language of your choice, and then sending that info to the Gluu Server via SCIM. In fact, that's how we're handling registration for this support app (in django).
It will be much easier for you to customize the enrollment process if you decouple it from the Gluu Server.
Feel free to reply.
Perhaps someone from Gluu support will have some tactical advice if you think customizing the Gluu Server registration page is your best strategy.