Targeting body parts?

I still have lots of things to train little Ben but as people keep on asking if he is a girl and he still quats to pee I really would like some ideas on targeting his hind foot so I can get him to pretend to pee on command - think it might be a bit of fun
Also I am interested in how to target other body parts like the hip and stuff cos I think that would be useful in some backwards tricks (of course I have to get him walking backwards properly yet - but he is getting there)
Targeting the nose was easy, front paws not so much but he has got is now - has trouble with right and left and if I tell him to 'paw' (right paw) something up high and he puts his left paw up then realises he often tries to put the other paw up too and falls over
I know it will take a looooong time - paw took over 4 months and I had to try many different methods as he didnt naturaly use his paw (he does now!) and when my mum spent a week picking his foot up the old style training I could see the look on his face 'hmm crazy lady wants me to sit then she picks up my feet then she feeds me OK, you pick up my feet all you want'
eventually I had to hold a treat above his nose over to one side till one paw unbalanced a bit and click
then same again till it almost came off the floor then tiny bit off the floor

its funny cos moving tricks - leg weave, spin, circle - he gets them so quickley