I've been researching the refresh rate issue where Chameleon would crash if you specified a refresh rate in Graphics Mode, and I found this thread on insanelymac from back in 2005:
VESA 3 fix for boot sector.I got the PC_EFI 10.5 source and applied his idea to graphics.c, as well as un-commenting out the generateCRTCTiming section, and while it still ignored my specified refresh rate, it didn't reboot either. In the thread only a couple of people actually said it worked, and most people had the same result as me, so I wasn't surprised.
Maybe this is something you guys have looked at before, but if not maybe it's a place to start. I don't know.
I know most people probably don't care about refresh rates anymore because they have lcds, but for my project I'm using an old crt that only displays certain modes, and none of those modes have 60Hz.