Presumably, you're reffering to http://www.rptools.net/toolbox/maptool/
We have no prior experience with RPG, it's terminology and the tools used to create such systems.
If we're to try and assist, we'll need a demo (or at least a detailed technical explanation) of the functionality you're looking to implement.What would the envisioned Tersus app be used for? How would it be integrated with MapTool as far as the users of the system experience it?
For best results, use the Firefox browser..