For this one, we took a vinyl stencil cut on a roland vinyl cutter, stretched a screen on a frame, attached the screen, printed a couple of shirts.
You may not want to do it exactly like this, but here's one way that actually worked.
For this project, I used the image created in the document ConvertImageWithGimp - http://www.instructables.com/id/EJ6T5P8VDYEY95WJHN/
Here are the photos - http://flickr.com/photos/connors934/sets/72157594503018354/
There is also a process for taking the image created with gimp and cutting a stencil with the Roland Signcutter using the Fabuntu interface, which at this time has not yet been written.
This technique was developed in part through the guidance and advice of Ed Baafi and Amon Millner at the South End Technology Center Fab Lab.
There are a few advantages of using this technique. Having the image in the computer and 'printing' it with the vinyl cutter means that you don't have to get nervous about ruining your original artwork. You can also scale the image up or down. If you want to make a small print on one side and a big one on the other side, you can just cut it with a different size. You also don't permanently attach the stencil to the screen with this technique, so you can use the same screen over and over by keeping it clean after each use and peeling the stencil when you need a different image printed.