Just stick your foot out by accident as they cycle by. It works a treat.
See, I prefer a loud "Boo!" as I cycle round someone walking on a cycle path...
Im sure the police would do something if it was actually affecting anyone.
Cycling at 10 miles an hour on an empty footpath next to a busy road is totally different to cycling madly through a busy town centre. I'm sure the police realise that and apply the law when it is needed, much like when you are speeding they may not stop you if it's only a minor transgression on a safe road...
(No I don't cycle on the pavements, I haven't cycled in ages as there are too many yobo motorists around where I live).