Hi LITTLEMISSMASSACRE
Here's what I did (bear in mind I'm no expert, just sharing experience with you)
1) GET A TRIPOD!!! Crucial
2) Set your camera to manual focus
3) Set to Shutter Priority (That would be T on the dial)
4) With the lights on, decide where you will stand while doing your light painting. You can get someone to stand there, or place an object there. Then go to your camera and manually focus on that spot. This is very important.
5) Set the exposure to 10 seconds or more. Check your manual how to do this.
6) If you don't have someone to trigger the camera for you, then set the countdown timer . Typically I give myself 5 or 10 seconds to trigger the camera, turn off the lights, and run to the predefined spot (step #4 above)
7) Once the camera triggers, you can do your painting
Just remember to write it in mirror-image if you are facing your camera, otherwise your TAYLOR will come out reversed !! hahahaha...
Have fun! Don't worry if it turns out weird, keep trying!
Here's one that I asked my son to paint ... (first time linking a picture here..hope it works)
http://picasaweb.google.com/lh/photo/R3f8a97DZU6-8XxXhO-ddw?feat=directlink