I would venture to guess that since they don't have it advertised on their site in the parts section, nor does Universal Jems.com seem to have any, that you'll have to find some rubber padding material & make one yourself.
I did something a little different when I re-finished my Ibanez RG7620. After sanding & cleaning that thing out of there, once all the re-finishing was done, I replaced it with a piece of mirrored plexi of the same thickness. I got a piece from the scrap bin @ Tap Plastics.
I'm not sure where you're base out of, but when I did mine, I lived in California, & there are many located througout the state. Now that I live in Puyallup, the closest one I've found is in Seattle, just a block or 2 from the EMP.