I however am oldschool in some regards. I don't feel the need to download a new program when winzip works just as fine. (Especially with that: add to DIRECTORYNAME.ZIP file. *chuckle*)...
However, They are right, look at the basics first, like the .skin files, or .sab files. Those will allow you to see how they do what they do. Then try mimicking them. A year ago I was just making a model package for Jedi Outcast, and felt so cool at just being able to script changing a robed model to an non-robed version with a key stroke. Now, I can change game play..etc..etc...etc.
The first and formost thing to remember: This is a computer, so unlike the XBox it is one big UNDO button. No matter what you do in your own "pk3" file it won't hurt anything. So play around and have no fear of the game going *croak* :sheep: Just erase your pk3 and try something new. Remember never to modify the original game stuff, just seperate it and know that anything in your PK3 will override the old information. When in doubt: Guess and Check. (i would recommend though, having a rather stalwart system to do this on, constant running and closing of the game is hard on the computer).
Secondly while doing development, read up on CVARS, I don't know where the list is to post here, but do a simple search, and you'll find countless descriptions of Quake3 based games cvar list. (or type cvarlist in the console for all the cvars it can list, then try "cvarlist a" for all cvars beginning with the letter 'a' etc, etc. This is because the Console cannot list "all" of the cvars at once. The same is true for the 'cmdlist' command, which privdes a list of commands that can be entered.)
Finally, Set the 'developer' cvar to 1 so that all the added information is printed to the console for debugging purposes. Then just dive right in and have some fun.
As for the visual aspects of the game, you'd have to go to the modelers and mappers. They work in a visual market that I have no 'real' understand of. if you have any code based questions (ie: menus, icarus, skin files, sab files) feel free to ask, i'll help anyway i can.
Jaeden "Sifo Dyas" al'Raec Ruiner
All the JK3 console commands can be found at jedimoves.com Just click on that link and it'll start dloading.