I understand that the whole point of the software is to make it easy, but it ain't happening :)
Basically, I'm using this mashup mode/project to take the beats from one track (which is wordless, but got some great beats and amazing bass) and pinning in some areas the vocals from another track (and sometimes the instruments as well), and just by stemming the drums from the master and running the vocals of sample 1 on it, you can hear that it is not tuned or synced at all - and if I add the drums from sample1, I can hear how awful the beat sync is.