How about a new key?
It would be equivalent with pressing '5' when entering the room, from then it'd be the opposite of the previous move: q-w, 1-9, 2-8, 3-7, 4-6, 5-5. So instead of endless qw'ing, you'd just press '0' until all the roaches are gone. A lazy smitemaster is a happy smitemaster
A variation to this (though I realize it would break the tradition of 1 move/keypress): the Lazy Like Hell Smitemaster Button. A single press of that would make qw'ing instead of you until there's a continuous supply of roaches.