Masud,
If you haven't looked at it yet, the Integration Manager is basically an MS Access application that allows imports and updates of GP data without having to worry about the logic.
If you can populate an Access table (or just about any type of list) from your ASP site, you can have Integration Manager populate GP from that table. Although not as clean as having ASP manipulate GP, it's much safer.
You can create your own integrations, using as many or few fields as you'd like, and script them to run your imports in a batch.
Not a problem.
Ray