Darren, I am afraid that if you sync a "doo be doo" or another vocal riff to a style, it will be out of tune most of the time. The synced part works as a second rhytm track and its pitch cannot vary. The only way to have a sampled part changing tonality with the different chords of a song is to use it as a sound to be played from the keyboard (left or right part), in real time.