If you search in the Market for "Screen Capture", you'll see an app with a little icon that looks kind of like the iPhone camera app.
It's made by a Japanese developer so the setup page is in Japanese, but gives you instructions on clicking the ok buttons (it's not that hard even for someone who can't read Japanese).
I'd really recommend it, because all it requires is installing the app.
No rooting, no tinkering, works just like buying a new keyboard from the Market and installing it. It also worked for my friend who uses the Droid Charge 4G.