Well, if you know the length beforehand, you should be able to make a bed and set the voicetrack as VT.
If you want it automated, you could create a bed with xx seconds in length and set the 'Next' Cuepoint right at the start of this bed. If you insert the voicetrack right after the bed, it should be played on top of the bed.
If the VT is longer than the bed, the bed will still be playing when the track after that starts..
I'm not sure how to otherwise automate it, perhaps somebody knows a way of doing it with the aux-players (load VT in aux1, the bed in aux2, play both, wait for aux1 to finish, stop aux2 and Play Next?)
- Rogier