You can download the exe-file (for Windows) or the source updates (a diff file, now outdated).
VGM logging is complete with a new menu entry and support for YM2612, PSG, PCM and PWM. (VGMs are logged to the "GYM dump" folder.)
Almost all vgm players support the YM2612 and PSG chips. The PCM and PWM chips are in testing state and you need my vgm player (called VGMPlay) to play these files.
You can download some example vgms here.
Although vgm logging is almost complete, there's a little problem with the timing because the sound emulation of Gens/GS is not (but almost) sample accurate. So Kega Fusion is still recommend to log usual MegaDrive/Genesis VGMs. I'm sure GerbilSoft can find a solution.
Also I want to ask, if some people that are very familiar with 32x hardware can help me to find the best way (I.e. small files) to log the PWM. (Currently I'm logging every write to the left/right channel, like it's done with YM2612 DAC.)
One last note: I already optimized the PCM logging, but uncompressed files are still huge. (30 MB for 2 min, but my first 2 min PCM log had 120 MB!)
I've wrote a small tool to optimize SCD PCM vgms. Download OptVgmRF exe or full source. (VGM Spec. 1.60 is here)
EDIT: Changed links due to some updates. Added OptVgmRF.
EDIT2: Fixed a bug in OptVgmRF that prevented it from optimizing the RF5C68 (the Arcade chip) and added OptVgmRF source.