This would be an excellent feature to extend the expression possibilities of VIPro.
It could be implemented (although it would not be a perfect solution) by applying a special fade in to note transitions (it could also apply to portamento). This special "fade" is more like an envelope attack control, so you can set start level and time to reach %100 volume and perhaps a curve value to give even better control.
I think this could be built into VIPro but it's up to the VSL team to decide if it adds enough value for the effort to implement it. Also they are the only ones able to try it out and see if actually works well enough to be useful.
I would certainly vote for its usefulness. The more we can shape the sound the better.
Tom