Before you try to do this, you must have found the elevator and have got it working. Once you have done that, use it to go to to the 2nd Basement and go behind the elevator. I have no idea how it is done, maybe a glitch or something like that, but it will look like you are walking on the elevator. You can even go to the back and walk south and you can push on what seems to be nothing.
In the basment chapter 1 of monster house gba as jenny the 2nd bathroom in the game I was spraying the the toys to the right. Right is -> this way on accident I dashed right into the toys and I inside the toys