I don't think it would be THAT hard. You pull up the middle panels and remove the clamshell, then just replace the horizontal carpet. It peels up off the gelcoated floor pretty easily. You'd probably want to remove the side panels and the drivers seat. And the kickpanel. I think I would not replace the carpet in the trunk, I'd just try to hide the seam back by the gas tank. Or, you could go the extra mile and pull the back seat backrest and the gas tank. My pal did it on his Brendella over the winter, it came out looking good.
I think I would spring for the good carpet from Toyota, the lowes stuff is pretty thin.
It looks like contact cement that holds the carpet down.