Alrighty, well, I went out and bought myself a new keyboard, partly because after about a year of typing on a cheap 10 dollar keyboard some of the keys got harder and harder to type on, and partly because my wrists were starting to hurt. So I went out and got a curved keyboard for 20 bucks. However, Microsoft seems to think that volume control should be done by 2 buttons, 1 up and 1 down. However, I've gotten quite used to the wheel my cheap one had, and I liked it as it gave me more of a quick 1 motion volume up or down. So I went ahead and ripped apart the old one and took it's volume control and popped it into a project box, the box is about 3 bucks from Radio shack, and the keyboard cost me 10 a year ago, so 13 bucks for a nice analogue volume knob still sounds like a deal to me.
Step 1: Get a cheap keyboard with a volume knob / use your busted one :)
Keyboard assembly is pretty simple, so I dunno if this should be a step.
However, just take all the screws out, and remove the controller board, which on the cheap keyboards is normally one board that has the 3 LEDs on it for the lock keys, and it'll also have a jumper cable headed over to a daughter board that has the volume knob on it. (I already stole the volume knob in this photo)
Step 2: Assemble
Get yourself a project box and just fit everything inside. Drill your holes and put your wheel where you want it.
Super glue the daughter board to the top and then put the wheel on it, and route the wires so that they don't get ruined when you close up the box.
You're done :>