I don't have any experience with the steam version, but I do know that it uses a different path from the standard CD version.
But what is even more important: Can your mac handle self extracting archive-files for PC and windows setup routines?
If you can use the windows setup, you have to make sure to set the installation path to your bloodlines base directory;
else you have to find someone with a PC, extract the archive on that, and manually copy all the files of the mod into your game.
I don't know if this answers your questions, but there's nothing more I can tell you.