Registration Page for Editors

There is any way that I could create a registration page for other function of the user?

For example:
I have 2 users type – User and Trainer
The 2 can be registered by a register form. But I want an especific register page for the second user type, when registered by this page, it automatically becomes a Trainer (and not an User like in the usual registration form).

I have been clear enough?
There is any way to do that?

Thank you.