Sorry for the late reply. Unfortunately we did not yet have a HSL shader variant available for SkeletonGraphic. Nevertheless I quickly created one for you to use, based on the original SkeletonGraphic.shader code.
Note that the HSV settings are not automatically updated when assigning such a material at a SkeletonGraphic and then updating the Material in the Project window, so don't be surprised that you might need to re-assign the material after HSV changes.
Also note that as with the Sprite shader, for brightness changes to work properly, the texture needs to be exported with straight alpha workflow (not PMA).
