That method is probably the best method to use making hash.

Yes, that will work. I have seen it done myself. The only thing is, is you have to shake the trimmings/ice in the jar for a good steady 20minutes. I mean, shake it hard so all of the trichs come loose.

Blend up your trimmings, and freeze them the night before making the hash. That will loosen the trichs making sure you get every last one Good luck.