http://opium.gbatemp.net/flashme/sl1vr.jpg
I don't mind giving it a go as I flashed my fat one, but I won't take any blame if I mess up :P
Basically, you have to short the bridge of the hole without touching the left side because that will turn off the DS. If it turns off during flashing, your DS is a happy 150 dollar brick. Why do we have to short the SL1? If we don't, we can't flash the firmware.