This seams to be a common issue.
...a temporary solution to the wet carpet.
On my GS400, I made a tray by cutting up a gallon jug and slipping it under the leaking box, attached a tube so water can drain. At first I had it drain in to a small plastic soda bottle that was tucked under the carpet but last summer I redid the tray and now the tube is routed through a rubber grommet in the floor board.
I have so far forgotten about the issue until I read threads like this, but I promise one day I will pull the dash and reseal the evap box.