To be honest, I'm not sure that not having the patch is the problem, but as for applying it:
(1) Get
Keka, which will allow you to open the patch, which is a RAR archive file.
[Memo to TPTB: Could we get a .zip version of the patch, since zip is natively supported on all platforms?]
(2) Open the patch file (available in the link in my previous post) by double-clicking on it after you've downloaded Keka and put Keka.app in your Applications folder. There should now be a folder called HotUv1.20Pack in the folder where you opened the .rar file. In that new folder, there should be some .exe files and Root_fs2.vp. You can ignore the .exe files.
(3) Rename the copy of Root_fs2.vp that's already in your FreeSpace2 folder to Root_fs2.vp.old, just in case.
(4) Copy the Root_fs2.vp file to your FreeSpace2 folder.
Also, just to make sure, when you look at your FreeSpace2 folder in OS X Finder, does it look something like this?
The MediaVPs_3612 folder is only there if you downloaded the MediaVPs.
I use the data/players folder to hold the HUD presets, which are files called hud_1.hcf, hud_2.hcf, and hud_3.hcf. They were in the retail install.
The wxlauncher.app doesn't have to be in your FreeSpace2 folder, though; it can be in your Applications folder or anywhere else.