I hadn't played it but got it with the steam bundle so I figured I'd write a table for it. Just activate the scripts then set the values for the flags to 1 to enable the cheat. It's all AOB scan so hopefully it will work for other versions.
1. Infinite health
2. Clip
3. Ammo
4. One-hit-kill
5. Good-Friends
** update 1 **
Added God-Friends cheat and One-hit-kill no longer kills allies in any case
How to use this cheat table?
Install Cheat Engine
Double-click the .CT file in order to open it.
Click the PC icon in Cheat Engine in order to select the game process.
Keep the list.
Activate the trainer options by checking boxes or setting values from 0 to 1
The god-mod and god-friend scripts do not work with some special character. So, I add my own table for this game.
Table for Quake 4 v1.4.2 (non-steam launcher)
1. Protect Tram Car
2. One Hit Kill (protect RHODES and kill enemies, not instantly kill some fliers, tram cars and the nexus brain)
3. God-mod (protect friendly units and your riding vehicles, except tram cars)
4. Unlimited Ammo Stack
5. No Health & Armor Cap