M.M.
Use a file.
I cut my son (2) once, and could never take clippers to him again.
I do it while he's watching his favorite cartoon and zoned out. Just sit him on my lap and take his hands. I use the roughest adult nail file that I can find (usually the black ones that you find in professional nail salons). That way, you only need a swipe or two per finger before it's done.