CGI in receipt function

[PCLearningMall.com]

According to the shopsite instructions an Order API can be inserted as a
custom CGI program. Here's what I am trying to accomplish, can any offer a
suggestion or source to help me with this:

On specific orders I need to generate a USERID and Password for a product
group I sell. This represents approx 10% of our total products. How can I
set it up that if a specific product is ordered that a USERID and Password
will be generated and emailed to the customer?

On the other 90% of the orders I do not need any special CGI functions to
occur.

Thanks,

Paul
www.pclearningmall.com