I can see that there are many questions already being asked regarding the same thing like:
Binding a datasource to a rdl in report server programmatically - SSRS
Most likely, you may wind up needing to run them in the context of the web application, and pull the data from the datasource into the report by hand.
I did this project a few years ago, and wouldn't mind getting it back up and running, and finally completed to support MVC/Web Forms/Win Forms/WPF/etc. as well as get it more robust.
This may get you on the right track.