Just kidding! I'm an ATGATT guy, but I wear textile protective pants with full armor on the street, and leathers on the track. I like how the leathers let me transition smoothly over the seat. That said, maybe some kind of a temporary cover for the seat when riding would help, something easily removable so it wouldn't harm your seat, but give you less slipping?
I think if you try anything like an alcohol that dries out the seat material, then it would weaken the vinyl and make it prone to tearing/ripping especially when riding with leathers. It might also dry the foam out prematurely causing it to break down.
I also found that after getting Tech Spec pads for my tank, I moved around a LOT less in the seat. Maybe try that first?