I have been using this for some time and thought it might be useful for you guys.
Pictured is one of the adaptors from my Mityvac hand vacuum pump kit. The inside is small enough to get a good seal on the carb cleaner tube. The out side fits most of the carb passages. With this arrangement I can flush out the carb passages with out leaks and with full pressure from the carb cleaner. I don't know if you can buy these separately. Might check at the auto parts store for vacuum block off fittings and then drill a hole. It works perfect though.
Danny
