Yep, the "rule of thumb" is to push the rudder towards the wing that is falling.

However, as Barry has pointed out, don't just practice belly-in without doing the same amount of regular hovering or you'll tend to get too used to pushing the rudder that way.

Your aileron input remains the same but elevator will work backwards although I had no problems with that when I was learning because up still causes the model to pitch towards the canopy and down still causes it to pitch towards the gear.

One good way to get used to hovering bot belly and canopy-in is torque-rolling. In a torque roll (or aileron roll in the hover) your perspective relative to the model will be constantly changing so you'll develop a "reflex" ability to put the right input in.

Practise on the sim and burn lots of fuel.