vBulletin Paid Account after Email Submit

Does anyone know how to do this or even if it's possible?

I'd like to give my forum members a single months supporter account if they fill in an email submit.

Is there any way to do this?

ideally I want them to click the banner, fill in the email, submit it then be redirected back to the forum with a month supporter access on their account. This is with vbulletin 3

Jez

I guess this isn't possible

Shame really, if it were I can forsee a tonne of sign ups on bigger forums.