After much debugging coreloop, now set to operate in it's own thread without having to obtain the Python GIL.
It's working and appears to be stable outside of FreeGLUT-related bugs. This can be demonstrated in windows refreshing after their size is changed or uncovered.
At this point the code has all been moved to Pyrex, even the coreloop thread. The latter took two days resolving a bug that turned out to be from Pyrex 0.9.4, we require Pyrex 0.9.5.1a (the latest release) which supports multiple cimport commands for parts of the same package.
Many thanks to Piet Delport for his help in resolving this!
So PySoy compiles beautifully now. Now to get widgets rendering again, specifically soy.widgets.Projector ;-)