I only know how it works in Windows, so mayhbe this is all obnsolete when it comes to Macs, but it never hurts to try:
When rightclicking on a folder, you can select an option which has to do with security and in it you can see who can view and/or edit the folder. If your username is on the list, check if you have all the rights to change the folder etc. This is because sometimes adminrights work only when logged in as an admin, so if you are logged in on yor computer with your own userprofile, it can block some of the adminrights. This can result in you not being able to make changes to a folder, and therefore you can't install the Launcher correctly.
Like I said, this is all a shot in the drak because it might work entirely different on a Mac, but maybe it will help you anyway.
By the way: did you install BF2 in the default location? Because it might help to do so for your computer to recognise the rootfolder correctly.
