I have a Mac as well. But I also have Boot Camp.
I used the SD card method:
- Download ROM
- Open with WinRAR
- Extract .nbh file
- Rename to "TITAIMG.nbh"
- Mount MicroSD card with a MicroSD to SD adapter w/ card reader (Best Buy =P)
- Drag 'n' Drop
- Put card into PPC
- Boot into Bootloader (hold power and camera buttons)
Flashed no problem
Read ImCoKeMaN's edit on the first post of this thread:
http://forum.ppcgeeks.com/showthread.php?t=16806
Or you could just ask ask a friend if you can use his computer for a night =D