I can't even get him to SIT on the potty for a second or two and I can't force him. It's crazy making. I wish Christopher would step up and take the kid into the bathroom with him but he's got privacy issues and doesn't perform for an audience.
It's so hard. When Ben was resistant, I had him pee in a cup. I got a big package of decent sized Solo plastic cups and had him pee in them. He thought that was great fun. When Chris was resistant, Scott got him to start by making an X (with their urine streams), which cracked Chris up.
I'm sorry Christopher has these issues. I don't know what to do about that -- at least not anything that doesn't involve a good cluesticking, and you might hurt your back, if you're too vigorous with the cluestick. I'm pretty modest (I think due to being an only child) but not so much with my kids, or I would never have used the bathroom for the first five years or so I was a mother.
eta...
The key to the peeing in a cup thing is to do it in the bathroom, over the toilet, and then letting the child get to pour the pee in the toilet, because (a) you're getting him used to going into the bathroom when he has to relieve himself, and (b) because they love pouring out the pee.
eta again...
And treating peeing in the cup like a funny joke fun, slightly subsersive thing to do doesn't hurt, either.