Keeping up with a cat's hairball treatment while away from home?

My fiance and I have a cat at home who has chronic hairball problems. We keep everything under control by feeding him a small dose of OTC hairball medicine from a tube each morning. However, we are getting ready to go out of town for a couple of weeks (for our wedding, then our honeymoon), and are trying to figure out how to keep up our medicine regimen while we are gone. I noticed that the main ingredient in his medicine is mineral oil - could I just add some mineral oil to his water while we're gone? Has anybody else tried this???