I've uploaded the latest MacUIM packages on http://code.google.com/p/macuim/downloads/list, and the MacUIM-0.6.0 is the first version of MacUIM using Input Method Kit (IMKit) in Mac OS X 10.5 (Leopard).
After some struggle with MacUIM IMKit version for Leopard, I think it becomes somewhat stable for the daily use now. So I've released it as MacUIM 0.6.1. Please check http://code.google.com/p/macuim/