Hello!
Possible, yes. Just not for me. =(
To do that I would need to extend VisuStella's plugin, but since it is obfuscated (and due to their terms of use) I have no way of checking what to change to make that happen. Skill Mastery already have script calls and plugin commands to gain skill levels, or add skill XP, you just need a way to have them called from the skill learn menu. You can try talking to VisuStella to see if they are willing to add this compatibility for you.
What I can do is just add a new skill type parameter value to stop actors from getting skill XP from each battle, but the other part can be done only by VisuStella. Sorry =(