It works, but...
 

Thanks for the help - I am using 10.5.8 from a legit Delta Upgrade from Apple on an AMD Athlon64X2 6000 box (3.0GHz).

Your instructions got my volume icon back, and working, but Apple's Audio & Midi Utility crashes on launch. I am launching to make sure that audio has not been switched back to 24bit - although I have had no problems with sound so far. I am also unsure whether VoodooHDAHelper is resetting the audio volume correctly now either...

PS. I have a horrible VIA integrated HD Audio chip 1708B or something horrific on an MCP68 chipset, so I am happy to get any sound in or out at all! ^_^