In
Colemak Academy, start from Level 1 with the setting:
"Colemak DHm".
When you get over 10wpm and 95% accuracy in a level, go up one level.
After accomplishing the Academy, head over to
MonkeyType and start practicing by using the
"Colemak DH matrix" keymap emulator. I like to do 10 words per session only, so that I can see the progress happening easily. Remember to sign up in order to save the progress and settings.
You don't need to change the default QWERTY layout for the computer for this to work. Colemäk will be stored in the keyboard's memory once you set it up, if I understood correctly. (Haven't received it yet.)