well, I think that it is true to install this new graphic environment on a version such as 2.3.x is not good a idea.
Can we test online or dl a tarball ?
(also it takes me time) thus I think that it better of preparer the version 3.x with new functionality and graphic system
How invasive is your code ? A true skin engine might be a big work (if we don't to do something powerfull and easy) but a good css implementation would be great (for a 2.3). (gif looked good btw).
Alain.