Hi,
I heard that some folks within IBM have achieved this - using 600E latops for example and I think v3 HMC code. I have tried the same thing myself but this fails early on in the install stage dropping me into a DOS type environment which I cannot troubleshoot my way out. I was using a 600E ThinkPad - you may have more success with a PC type machine.
It is worth a try 'out of interest' - but of course you will understand that IBM would not support the use of a non-standard HMC device, though I'm sure you weren't planning on connecting it to 'live' systems.
Tim