I have been asked again about URL Access methods with programming again I can expand on the amount of information other than the white papers.   See my previous post.    I am at a conference for the rest of the week but will try and cover a bit more about this if required.

From the BOL  there is a lot of general info about URL Access and passing parameters.

There is a section on the syntax 

There is an introduction to Reporting Services Programming

The last one for now is Integrating Reporting Services into Applications 

I think this is enough to keep you busy for a while enjoy.