We have used the Emla cream, although I'm not sure I know what the Tegaderm is. I assume it's some type of plastic band-aid type covering. (I always used a piece of saran wrap with tape.) I believe the directions called for a dab of EMLA about the size of a quarter. I don't remember if I got these instructions from the pharmacists, doctor, or if it was on the package... but that was what I went by. (I'm all out right now so I can't tell you what it said on my prescription label.) We began using it when my daughter was about 7 years old (she's now 9) so I'm not sure what the differences would be in using it for your baby, but I thought I could at least give you something for comparison. My guess would be that you'd use less, but don't apply it too thinly. I never rubbed it in or anything, just put a blob of it on her and covered it up.