Affiliate Link to follow numerical sequence only

Hi I am using Post Affiliate Pro as a tracking system. I would like to get Affiliates and Post Affiliate Pro to designate the same Affiliate URL Link to each member as they sign up. I can set Post Affiliate Pro to change the affiliate link to suit all numbers and follow a certain pattern like starting from number 300 going to 301, 302, 303 and so on.

I need to get affiliates plugin to be able to produce a simple affiliate url as well. Is there a way to force the affiliate link sequences? Pref. Numbers as it is the only constant.