First you've got to flash Clockwork Recovery (CWR) - that's a bit tricky and creates some screen issues (multitouch, flicker, sensitivity) - CWR also wipes out the stock recovery so it's tough to go back to a stock Nook.

You also have to flash a new zip through CWR with all of those attendant issues.

Not to take anything from the devs - I mean, it's a great piece of hacking but it looks like a marginal battery improvement - I think I'll wait for "official" BN 2.2 - IMHO, a rooted 2.1 Nook Color is about 99.9% of what I need