I had a similar experience installing OS3.9 on My A1200T, it's got a Blizzard1230 MK IV, a powerflyer and has the timing fix.
Sometimes I could get quite a long way through the instalation before it screwed up, sometimes I couldn't and sometimes I could complete the instalation but when I booted into OS3.9 clicking anything made the screen go black and rebooted my machine.
Sounds like we have similar configs except for the accelerator. In the end I gave up and reverted back to OS3.0, which works good, I never stopped blaming the powerflyer though.
If you get it sorted drop me a line about what you did, it may help me.
