[Rhymes]

A while ago, I introduced a friend of mine to FreeSpace, and he loved it and wanted to get it. 
The problem is, he has a MacBook, running Leopard, so he can't just download it from GOG and use Turey's installer.
I told him I'd ask for help, since I know where to look (here) and he doesn't.  So the question I pose to you is: how does he go about installing FS2 on his Macbook?

[FUBAR-BDHR]

According to the Wiki for FS2_Open you just run the Mac version of the installer.   No idea how you install in the first place. 

[musicaleCA]

I would suggest getting your hands on a Windows machine with a burner (you sound like you own a computer with Windows), install FS2, and burn the entire FS2 folder to a DVD. Then your friend can copy the FS2 folder to /Applications/ so that he gets all of the original FS2 files in /Applications/FreeSpace2/ . Then he can use Turey's installer to install the rest to that folder.

[Jeff Vader]

That's what I'd suggest as well. Though you can always use a USB stick or an external HDD to move FS2 from the Windork machine to the Mac.

Hmm. Perchance I should cook up a sticky with installation instructions for Mac and Linux users. If only I had time.

[doomeru]

Here is what worked for me: Downloaded FS2 from GOG.com, ran installation using Boot Camp XP partition, then transferred the /freespace2 directory to my OS X partition's Applications folder.  Then you can either run Turey's installer or just put the nightly build, launcher and mediavps directory into the freespace 2 folder.  Don't forget to download the ogg cutscenes as well.

Without a boot camp partition, this should work the same way if you just install on an XP machine, then transfer /freespace2 to your mac.  For backup purposes, it might be a good idea to to burn it to a disc, though I'm not sure what the Freespace/GOG EULA has to say about that.