Crate, wire or plastic. Also include a favorite toy or blanket for a soothing smell.
You should crate-train your animals at home first so that the use of a crate in the car is not scary. I like to...
if you have a small can of refrigerant you attach the specially made hose to it. then connect the other end to the vehicles low pressure fitting. this fitting is always on the larger of the 2 a/c...