Crate training, I've found is alot more acceptable than harness training (my cats experience). Like jenluckenbach said, keep the crate out all the time. Put good things in it, feed him there. Most cats love the privacy it gives. My guys have to be convinced NOT to go in. Orangey especially ends up in crates he's not supposed to be in (gone to the car on the way to the vet with one, realising I actually had two!). The sooner you start the better. I'm sure you'll get a pet flight =)