Best option is to edit the music so that the beat count slows down to where you want it.
Programs like Adobe Audition can do a really good job.
Recently turned a good salsa song into a nightclub two step for a couples wedding. The song was "Could I have this kiss forever" (Enrique Ignasias)Some songs work well others don't depending on the vocals.
Otherwise the same program can splice two songs togeather but this is more difficult to do seamlessly.
You could also do it with some music systems as they allow that type of option as they play.