He figured a way to climb up, irrigating boots and all. It might not look too elegant, but it worked. It's true that when there's a will, there's a way, especially for a headstrong two-year old who knows no limits.
Once the door is open, he knows just what to do--get in the seat, put a hand on the steering wheel, and turn the key. Yikes! I had to jump in and turn the key back the other direction.
He manages to look all angelic while he's doing this. He was quite disappointed when I told him we weren't actually going to drive the tractor.