Membership numbers

[Fuzzy Orange]

We offer a paid membership scheme on my forum (106owners.co.uk)

I use the paid subscriptions system on vbulletin, as it allows renewal reminders and will drop people who dont renew etc...

However

When people sign up they get some free stickers (in a choice of colours) and a unique membership number

I would like at the point where it creates the subscription to ask the user to choose a colour of sticker, assign a new membership number to them (which is just a userfield), and then emails the entire order to an orders@106owners.... email address so there membership pack can be sent out

Whats the easiest way to do it? Is there anyway to add a trigger off the end of the subscription system - or would I have to write a new page which goes off to paypal etc.. then inserts the new subscription directly into the vbulletin database??

Thanks in advance for your time