I used a flathead jeweller's screw driver but I can't recommend it. You'll want something very conductive so as you don't need to "re-poke" SL1 to get the % to move.
The IMPORTANT THING to remember is to wrap the sides of the thing you'll use with electrical tape or something to make only the point conductive. You wouldn't want to short anything other than SL1. (if you're flashing a DS lite)
The traditional trenchcoat technique still works okay as far as I know.
I have the same one in my other 3 switches. it's never had a problem with about 10GBs of space left. I'm going to check it when I get it so it may be Wednesday before I start downloading games on the oled.