(1) Update Mac Jedi Academy to version 1.01C
First you need to update your Jedi Academy MP to 1.01C using the patch available here -
If you had the older JAplus client installed (the ones with the separate bundle files, where you had to rename all your dll files with a _ in the name), then remove those bundles and put all the dll file names back to normal (remove the _ from the name).
Run the updater to 1.01C. This will update your Jedi Academy SP and MP applications to 1.01C.
(2) Update Mac Jedi Academy MP to version 1.01D
Next, you need to get Jedi Academy MP version 1.01D, which is slightly hard to find. This newer patch hasn't been widely released, and has some new bugs (such as it always quits to the desktop when you try to return to the main game menu), but it will allow you to run the japlus client.
To get Jedi Academy MP version 1.01D, go here:
http://www.brad-oliver.com:8080/~boliver/JKJA_101d.sit
mirror http://www.japlus.net/japlus/JKJA_101d.sit
mirror http://www.pcgamemods.com/13253/
Once you install this (just replace your Jedi Academy MP application with the 1.01D version), your Jedi Academy MP game should now be at version 1.01D, and your Jedi Academy SP game should be at 1.01C.
(3) Installing JA+ Mod version 2.3
Now for the confusing part. As you might know, the mac JA has multiple gamedata folders- one is located here (i will call this 'Gamedata location #1')
Applications/Jedi Academy/
and the other one is located here, for each user that plays Jedi Academy (i will call this 'Gamedata location #2')
username/Library/Application Support/Jedi Academy MP/
most of your skins, maps, hilts are probably in the location #2; however for this installation we will be using the location #1.
download the full JA+ 2.3 package from here:
unpack that zip, it should make a folder called japlus_v2.3. Inside it are several files and folders.
Copy the entire folder named 'japlus' to location #1. It should be placed right in your 'Jedi Academy' folder, next to your Jedi Academy and Jedi Academy MP applications.
Replace any older 'japlus' folder that is in location #1.
Open the folder named 'base' that is in the japlus_v2.3 zip, and you should see a file called 'japlus_gla_anims.pk3'. Copy this file into the base folder at location #1.
That's It!