I have done some things with SRS. When it comes to consuming assemblies from RDL, I havent looked at returning data objects from assemblies, which is one approach that you could take.
I think that in most scenarios, the schema information is pumped into the RDL by the report designer, so it is feasable that you could probe LLBLGen generated assemblies and use the information in the assemblies to create the RDL Meta Data required by the SRS Engine to run the report.
Good luck though.