JK, Joe has a great tutorial on this forum--- he uses either persimmon or pear for the tutorial but it is the same for citrus. It also scales down really well-- I posted a picture of one of my toothpick sized bark grafts on the photo forum. The trick with toothpick size wood is to get at least a 1/2 inch long bevel cut and then take a very tiny slice off of each side-- I used pencil size rootstock for the toothpick size scion.

Good luck!

Thanks, Skeeter. I'll check it out.