There is a separate build of fastboot for Mac you will want to download. In fact, the Mac was the first platform supported by kindle fastboot, and I think that the binary executable is still available at yifanlu's website (and probably download links in this forum too).
MfgTool is only for windows though, so if you need it, you should run it in an emulator that has USB pass-through support (I use VirtualBox), or it may run in a WinPE boot CD too (I have not tested that).
EDIT: I see that you fixed it. Great!
Last edited by geekmaster; 05-17-2012 at 09:21 PM.