I cut my last one (last week) by drilling a hole in the side inside the drawing I had made on the side, then roughing it out with the saw StewMac sells for creating bridge pin slots in the bridge. Then I carved it to the lines with a sharp knife, and finally finessed it with files. After that I created a reinforcement (piece of extra side with the grain 15 degrees out of line to prevent cracks) and HHglued it inside the guitar and repeated the process above till it fit the port.
Looks like this:
