The second principle of abuse protection is teaching them what to do if someone does touch them in a way that makes them feel uncomfortable. This shows the abuser that the child is not going to just sit there and take the abuse. Ask the children who they would tell if this happened to them. They need to know to keep telling until someone listens to them and helps them. The third principle is role-playing.
Children learn by doing.
Then you can test them by giving example situations and asking what they would do. Then role play the situations with them over and over again. Make sure they understand that you are pretending, and give them big sloppy kisses and bear hugs they do not like. Give them every possible situation you can think of. It is not necessary to scare them to get the point across.