I said I'd left, but since you've asked me a direct question ....
First, I know how hard it is. I had a toddler and a baby. Toddler did not like walking either, and was prone to fits of violence to his little brother. I was sorely tempted to smack him many times, but that would have been me just venting my frustration.
I had a buggy board, and that helped. Some toddlers don't like to walk, some walk very slowly. If you don't have a buggy board, I would let him walk, but then as soon as he plays up, he goes straight in the buggy. You then tell him that if he can't walk nicely, he has to go in the buggy.
Or, you put him in the buggy to begin with and tell him that if he behaves, he can have a sticker on his coat when he gets there (actually, you could try this with walking as well).
Just one idea. And i know you think you can't trust him ever, but you will be able to.
If you let him get what he wants for poking his sister in the eye, then he'll keep doing it.
I am sorry if I have come over as unsympathetic on this thread, it was not my intention. I said earlier how hard I found the toddler years. But I can't pretend I find smacking acceptable, because I don't.