If you want to create a keyboard layout or use a new layout, this is the tool: http://www.microsoft.com/globaldev/tools/msklc.mspx

I've been playing with this Portable Keyboard Layout utility and it works nicely: http://pkl.sourceforge.net/

You can also try it online: http://blite.iki.fi/lab/alternative-keyboard-layouts/colemak

You can download a ready-made keyboard installation package at http://colemak.com/Windows.