making "caps lock" or "capslock" be the "control" or "ctrl" key (same thing) with Debian Etch PPC and AMD64 (probably applicable to many linux distributions)

type: "man xmodmap" at the terminal and read the parts about finding the key codes using the command "xev". The following page explains how to do it well:
http://ubuntuforums.org/showthread.php?t=420705

So after some playing around with my .Xmodmap file and .xsession file in my home directory I have this in my .xsession file:

xmodmap ~/.Xmodmap

this in my .Xmodmap file:

keycode 66 = Control_L
add Control = Control_L

remember to use xev to find the keycode for your caps lock key. 66 is mine on a G4 mac.

So when you are done to get this working type

xmodmap ~/.Xmodmap

This way you can start using this immediately; otherwise, it should work if you restart X.