Dittoes on the above. When cats are used to doing things one way for a long time, it's very stressful for them, and very difficult for them to change. I don't say it's not possible, but if you really need them to stay out of the bedroom, put some cardboard on the door to protect the finish and buy some earplugs for you and your friend. Eventually they'll get used to it, but it will take some time. And if this is what you decide to do, NEVER give in. 100% consistency and persistancy is the only way it will work. Give in once, and you're back to square one.