Often times these medication can be formulated into flavored liquids that aid in administration (think tuna flavor :B)
Our Henry is the same way with the initial movement, but settles after the first day of travel.
I don't try to pill him, I just use the injection form of Cerenia. This is the best medication I've found, but it only comes in pill or injection and I'm not sure your vet would provide injections for you. I carry a bottle for us :B
There are a bunch of OTC medication that might be helpful. Rescue remedy for relaxation, lavender oil as aroma/scent therapy (not given orally), ginger is a natural product many people use and I've heard of people using it with their animals.
Doug, DVM