Oscommerce Referral Rewards Scheme

I am setting up a new oscommerce store, unfortunately having looked around I can't seem to find a versatile enough affiliate contribution. How I want it to work is say customer X refers 5 customers to me,every time any of those 5 customers purchase, I want to be able to pay them a fixed rate comission or a percentage of the sale. It's important though that I don't want referral links, i.e. code in the url, customers can't sign up to the site itself, so I set each customer up, it is at this point I would like to enter the email of the person referring them to me, so each time the referred person goes to the checkout their email address is drawn from the database and when the purchase is complete the associated comission is allocated. I will be taking payment primarily through paypal, but also cheque payment so I would like the comission for anyone paying by cheque not to be allocated until the cheque is received not when the order is actually put through. As for the comission I would like to be able to have two options for each person, either store the comission they earn to use in the store later(which would also mean an addition to the checkout process to enable them to use the? comission, and I would like also to be able to set a limit before they were able to use the comission against a purchase)? or perhaps in the future to request the comission as a payment by cheque to them. I would also like to be able to set a limit before a comission payout could be performed, i.e. £25 etc ## Deliverables The end product required is not a complete install of OSCommerce, The oscommerce setup I will be using is a quite heavily modded install of oscommerce 2, as such I would need the code provided along with instructions of on what page and where to instal;l each piece of code, basically like the contributions within the oscommerce site are