Spoiler:
It's impossible if you're in the 1-space corner, you need to reach the top. To do that, you need to die without moving left, then exit from the left. If you've already reached the top, then push the rock onto the conveyor.
- Go down and right to hit the 3-flag
- Go right, then die by moving up and down
- Go up and left to reach wormhole
Once you're in the 2-space corner:
- Hit the 3-flag again, then face left
- Go up, then right, then back down to align the top cat
- Hit the top 3-flag, then push the rock into the spikes. It pushes you back down.