Son NOT Willing Too....

Maybe your son has gotten a message somewhere along the way that it's not acceptable for him to touch himself "there" and is carrying that over to bathroom time. If you have a close enough relationship with your son (we mothers have GOT to be able to talk to our sons about anything and everything!!), show him what happens when he doesn't hold himself to aim--and have some clorox wipes or something for him to clean the tinkle mess. Maybe he has a sensory touch issue that could be worked on through occupational therapy (o.t.). And be sure to reward him with positive praise when he does not make a mess! Make a BIG deal out of it!
Good luck!

Is there an uncle, grandpa, or male friend who could help him? Maybe he needs a man to direct him by "showing" him. Otherwise, could you suggest to him that he hold it? I am not sure of what his special needs are, so I am not entirely sure what he is capable of doing/understanding.

Just go in and explain how important it is for him to aim for the toilet, make a game of it, my 6 year old doesn't always hold himslef either and makes a mess, so I bought some of those Clorox clean up wipes and keep them by the toilet so is he misses he can clean it up, that has helped a little in holding it properly cause he really doesn't like to clean it up. I think it isn't abnormal, just him being a kid and trying to take a short cut :).

Give him something to aim at. Cherrios, fruit loops.
Or tell him if he can't try then he needs to sit!

My goodnes, I think I just found the problem with my boyfriend and son, they pee all over the place (lol) not really that bad but I just have to giggle a little, boys are so funny, I hope you can teach him to aim.