Just to make it clear, I wont take any responsibilities from the damage you might cause by following my instructions and so on (not that this would be any dangerous), so if you cant use common sense, dont blame me. If you doubt yourself at all, dont even try this.

You could also reinstall and do something while the installer takes its time. Or you can do it my way, which takes 10 seconds (I got the files in a folder at my desktop).

Theres are 2 ways to do it, with one you can play 1.0 q4base + mods and the other way only the mods work.

Update (22.4.2006):
Quake 4 version toggle utility by Shokd (1.0, 1.1 beta, 1.1 final and 1.2)
DOWNLOAD (Apparently shokd killed the link)