Report with AsOfDate parameter

I need to create a report with an AsOfDate parameter that is used for filtering the data (dates in a table that are the same month as the parameter) and in a field calculation in the select clause (months between another date field and the parameter). I’m still new to ASP.NET Maker. Am I missing something obvious that makes this doable?

On a side note, supporting stored procedures for reports would be huge for me. All of my reports are generated via stored procedures. I know it is doable because the code generator I’m converting from supports stored procedures (but it’s weaker than ASP.NET Maker in many other areas).

Thanks,
Craig