Web Application User Authentication

Question

I have successfully implement ADFS login using AD users in web forms application. The problems is I don't want that user to be a typical domain user with which one logs into windows nor do I want to have so many attributes. For instance, I would like to have a custom user or account object with may be 4 attributes for each web user and organize them across ou. At the same time, I want ADFS to authenticate that custom web user like regular AD user. Please, let me know how I could accomplish that. Perhaps, you could point me to hands-on example.

Thanks in advance,
RG