Custom Bard Versatile Performance

[athelu]

So, I like how the Bard Versatile Performance ability works, where it allows you to substitute one skill's ability for another. I am trying to do something similar for a custom class - where the users Concentration "skill" is used instead of a regular skill. I thought had it all figured out, but am getting tripped up on the "Special ability category".

The process that does the heavy lifting for Versatile performance is a an evaluation script in general-->Procedures called "ApplyVPerf". I have made my own version of this script for my custom class and am calling it, but it gets hung-up on the Special Ability category.

Can anybody tell me where these are stored in the system? I have tried just adding a "new blank" to the list on the class custom ability picker, but this does not seem to satisfy what the procedure is looking for.