Running Mac OS 10.5.1 on the new MacBook Pro. Running 10.4.11 on the old G5
The settings are stored in the preferences file. You can find it in your Preferences folder in your user account:
1) Open your home folder.
2) Open the Library folder.
3) Open the Preferences folder.
4) Look for the file "com.camerabits.PhotoMechanic.plist" and copy it to your other system in the same location.
HTH,
-Kirk