Jade, I was having the same problem that, quite by accident, fixed itself.
I'm running 9.2.2/OS x.3.9 on a G4 with Toast 5.2.
What I did was started Toast, THEN went through the steps til IT ASKED for a disk. For whatever reason, it worked that way. Maybe it'll do the same for you...
There are no drivers out there for the 109/Mac. .... Good luck.