OK, after lots of playing around, I've almost made everything work.
I can access Genesis Prefs, and I've basically cloned settings from my A4000 system which is now offline. OS3.9 on it also uses Genesis and once I was able to access it in MOS it was very easy to set everything up as I am already familiar with Genesis from the classic AOS usage.
Anyway, I can get as far as the Genesis Connect / Disconnect screen, however as soon as I click on Connect, the Genesis window would freeze. I suspect that the MUI classes required that I've added (as per what Snoopium failed to read) were not all MOS specific, and some were from classic AOS. Does this matter?
Is there a place where I could download all, or most of the latest MOS MUI classes?
Thanks.