I’ve done a little treadmill skinning, but not much. It is specific, but I found several disadvantages:
* More drag with skins-on-track than skins-on-snow;
* Boot/foot issues, probably because there’s less give in the underfoot surface;
* Wearing of the skins, pretty quickly;
* Much bigger sweat factor inside boots;
Now, I weighed that against outdoor skinning, and I have great nordic options nearby. If you don’t have any snow at all, then it may be worth it.
To make it work, it may be worth buying a ratty old pair of skins or perhaps not using any skins at all. (But watch for wear on your bases and/or damage to the treadmill from your edges.)