Marvellous! I tried the Stockyard Return level on the PS, and this trick does indeed work! Step into the screen from the right, but don't walk any further to the left, so that Abe remains off screen. Remain standing and throw
down. More often than not (but not always), the three bats chase after the rock as if it were Abe, allowing Abe to climb down as before.
The Slog has returned to where it was previously, so Abe is free to try and possess the Slig, but I haven't managed that yet. If you want to go and get more rocks, you have to return to the screen with the Slog, then immediately run back on youself. You can't jump over it before it leaps at you.
But quite frankly, I'm not sure it's worth the effort. Still nifty, though.