I know exactly what he means and I know what has gone wrong, but seeing I completely DONT have a Mac, I'd have no clue how to solve it.
As far as I know, if you wrote over the original files, it should do fine, unless of course the Mac uses images differently or anything like that, which seems very unlikely seeing other mods DO work with personal graphics...
All I could probably ask is if:
One: There are 2 locations for the _mods folder (still don't know where), maybe there is a need to apply the mod to both or at least the right folder.
Two: If you would do the above, back up the files you have there first. Then copy the backup files to the earlier folder which you applied the mod on.
P.S: I really really really really don't like the Mac. >_>