I've had several Kubotas with MMM's over the years, and all of the manuals said to simply back the tractor across the mowing deck.
Of course, it helps a LOT if the tractor has 4WD, plus I put some scraps of 2x6 in front of the MMM to act as a step up. But the mowing deck is plenty strong enough to support the weight of the tractor.
Tom.