Hi Tony,
Yep, the SP5m is fine, although you'll need to install the SP5m keymap file rather than the SP5 keymap.
I found this guide to be the best. It's step by step.
Kar Hoe's Blog - [GUIDE] Upgrading HTC Tornado to Windows Mobile 6
You'll need to:
Application Unlock,
Super CID,
Wipe the radio,
Install a custom radio,
only THEN can you install WM6.
.....but it's not as hard as it sounds, and the guide I've linked to above is very good.