I did it with tile, not hardwood. It was not a problem. In my case, the tile was thinner than the carpet. I guess you might get some interference if it was the other way around.
After I was done, I put a wiper of felt under the edge to keep crap out from under the slide.
I think it actually worked better, the carpet kept getting wrecked the way the slide was arranged. Also with all the slideout leaks I had, the carpet was hard to get totally dry.