Update

Simultaneously I had a word with patali, regarding pyGE if something similar will work with Google SketchUp.
We can go with an external script, that will sends TUIO using win32com directly http://code.google.com/p/pymt/source/browse/examples/kaswy/PyGE_touch.py
like passing commands. That's how the Google Earth is controlled via python and we can make these commands user defined
1. We run an external script and this script launches the Google SketchUp
2. Takes in the TUIO, processes gestures and talks to SketchUp

But we will resort to this option if all else fails, after trying this successfully I'll come back to usual TUIO implementation within SketchUp. Started to try if that works out with Sketchup. The only difference being that Google Earth comes with a direct WIN32 COM interface and SketchUp doesn't. But we might be able to add that support via a DLL.