good question, if you're not sure, take the strings off to separate any common link between the bridge and stop piece, plug in your amp and touch your hand against the bridge, and then the stop piece, whatever one stops the hum you found your ground.
If you insist on grounding it to the bridge you'll need to:
1) Pull the treble stud-socket
2) Drill a small hole sidewides from the stud-hole into the control area
3) Cut a 12" wire, pretty small gauge. Strip 1" bare. Run the wire through the hole, leaving the bare inch inside the hole. The wire should run vertically up and down the hole. If it sticks out you can trim it with a razor knife when you're done.
4) Start banging the stud back in. Strip the other end and test before you finish.
5) Finish banging; cut to size; solder; make music.
Ah, I understand what you're saying now. The only thing is, where exactly do I run the wire to on the bridge? I'm looking through the f holes and can't find anywhere. pickup cavity? Sorry, I'm used to solid bodies and I'm a noob with semi-hollows. Lol