In order to "Cliker Train" you don't need to use a clicker. I free shaped with my two older dogs to teach them to retrieve a stick from the ground and hand it to me (a Lab and a Lab mix that don't play fetch...weird, I know) and I never once used a little plastic box with a metal slab in the middle.

The marker word I use is "Yes!". At the moment when someone using a clicker would be clicking, I say, "yes!" It's simple, not a word I use much in day to day conversation, short, it leaves my hands free, and I always have it with me.

I agree with the training methods listed above. "Hold it" sounds like a good command to use.