I tumble with Zilla, the grains are so fine they don't make depriming tougher. (Walnut would sometimes get stuck in the hole above the primer, you'd have to crack or push the piece before you could star on the primer.) All I do is make sure the case is straight in the shell holder. I use an RCBS Jr. 3 press; not as much leverage as a Rock Chucker, but more than enough for depriming.
I'd say developing a 'feel' for what the pin is doing is the key. It came naturally to me, but you might have to work at it. Go slow when the pin makes contact, you'll soon get a feel for it.