Well, I managed to finagle one up by myself.
It's functional, though I have no idea if there are bugs.
I would have preferred changing the icon padding and size, but changing these settings in the xml appeared to have no effect. No idea why not.
The conversation on the server suggested there was already a fix somewhere, or rather someone told me they didn't have to update (or someone updated it for them) from the "drumsui forums", but I was not able to locate any such site. The only drumsui forum I ever found was the one here, all other google results (that I bothered looking at) were other forums referring to drumsui.
Anyway, it is here: