Well, if all else fails:

 strace -eopen python <scriptname.py>

will let you know where python is looking for the pygtk files. Knowing that, you can tweak PYTHONPATH, --prefix, require() and other assorted nasties to get your versioning correct.

Don't write to the mailing list complaining, because we all know it's hard to make it work. You'll have to debug yourself. Next time complain when a solution that brings endless hassle to installers is implemented!