One thing that's missing is an abstract interface like the PointsToAnalysis interface which gives you points-to information without having to know anything about the underlying points-to analysis implementation. The current PointsToAnalysis knows nothing about contexts. Probably this should be one of the first things that we should design, so that you can get the information you need without worrying about the implementation.
I didn't want to design this interface until I had some client in mind that would use it, to give me a better idea of what information it needs to provide.
Anyway, I think the simplest way to extend it would be to add a new version of each of the reachingObjects methods that takes an extra Context parameter. Would this give you the information you need?
-- Helge