I forgot to mention...
Of course, it depends on how much of the original Mega Voice and its track that you want to re-use. For example, if you don't care about the FX noises (C6 and above), then they can be deleted.
Another example. In the case of Mega Voice Single Coil Guitar, the open string sounds are triggered by velocities in the range 1 to 60. If only open string sounds are required, then one possible approach is to delete any note with velocity 61 to 127 and simply scale the remaining notes to cover the full MIDI velocity range 1 to 127. Purists may blanch at this idea (!), but it is fast and I've used the technique a few times. The ear is sometimes easily fooled...
To re-use dead, mute and hammer on sounds, notes in the appropriate range must be selected/filtered and copied to a track of their own, assuming that a dead, mute or hammer on VST sample is assigned to the corresponding individual tracks. The actual VST instrument may allow articulations within a single MIDI channel with its own mapping.
Accuracy and precision come at a cost in human effort.
Re-using a Mega Voice track is pretty labor-intensive.
All the best -- pj