Before you invest a lot of work -- not to disuade you, but to make sure you know -- there is only one way to add skins to this scenario, and that is for them to be accepted as skins by HTC in the Main Arenas.
Skins are either built into the terrain file at the time the terrain file is built (this terrain is already built, so that option is out), or they are put where all other Main Arena skins are put, and HTC won't put them in there just temporarily. They have to be a regular acceptable skin.
So, there is a fairly high bar to get skins in for a scenario.