Great news, I settled on a design that works around a number of the issues I've had to deal with. After a few days of hacking away I now have a function unit testing framework working, including a small battery of unit tests for the framework. I've got some code clean up to do and then some docs to write on how to write tests in this framework (I had to make a few steps away from the traditional xUnit approach, but they're not too bad). Hopefully I should have everything ready to post in the next day or two, assuming no major distractions.
-Mark