Fingernail clippers or small manicure type scissors. Make sure they are sharp. The notches last for many successive sheds. Obviously it is more difficult with smaller species or neonates. In the case of neonates this method will not last as long due to the faster growth. I won't get into a "pain" debate here, but I don't think this scale clipping is anywhere near painful as notching a rodents ears. You should not cut deep enough to draw any blood. It takes a little practice, and remember to make detailed notes of the pattern of notches.
:eb: Scotty Allen :eb:
"For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return." -- Leonardo Da Vinci