Dan has little travel sizes, but I don't think those would last you three weeks. You can take the regular sizes in your checked-in luggage (if you plan to fly). The 8oz size will be enough for those three weeks. Just pack in a big gallon size ziplock baggie, lock the pumps down, and pack them in your suitcase.
The Regimen can be done just about anywhere. I've always taken it on vacations, camping, etc.