Paid Subscriptions Custom Fields?

[Code3Services]

I'm needing a way to add a form to the Paid Subscription process. I asked the question over at vbulletin.com but they sent me here.

Anyone know of a hack or addon that would allow this? An example would be right before the user gets sent to Paypal to finish the process, it would simply require a few fields such as:

Name
Address
Phone
T-Shirt Size
etc.

Thanks for your help!