Registration/Subscription

[jackcarr]

I need a hack which will enable users, upon registration, to choose a subscription type (I currently have three available, one free, two paid) BEFORE they can go any further. This is because I've built my site's login system around that of vBulletin. The link below is to a mod which has gotten me halfway there, which puts users into the appropriate group according to a field, but now I need to tie this to the registration page.
https://vborg.vbsupport.ru/showthread.php?t=82992

Please help, I need to finish this quickly.

Thanks
Jack