I install garage doors/ gate systems for a living.
If you are talking about a sectional operator its not that hard. The trouble is most of the operators have a rolling command structure, ie push button opens, push again closes. Not really desirable, for example you roof is shut and the rain sensor throws a command and the roof will open. I have converted 6 rooves using sectional operators now and they work quite well upto about 2.4 metre throw.
I usually throw out the electronics that come with the operator and use a different controller that allow ascom to control it with seperate open, close, stop inputs. And this board allow me to use limit switches, voltage/speed control, ramp up and ramp down, cloud/rain sensor inputs and heaps of other features.
Be aware that there are huge differences in quality between garage door operators. Make sure they are DC POWERED AND NOT AC. Ac usually has more grunt but you dont want the hassle of 240v.
If I get around to it I'll have to update my observatory thread to show what I have done. If you want I can make up a complete ascom controller the same as mine to work with a dc motor/ garage door operator. Doomsayer has also got one on his observatory, but his is a little more complicated.
I do not encourage non electricians to use 240v for safety. The merlin has 240v on its circuit board tracks as well, most 240v motors have 240v stepped down to 12/24v then have an external relay for 240v switching to keep 240v off the main board.
The standard merlin electronics are not suitable to use with 'cloud sensor input' which means you have to use a seperate 240v controller and playing with 240v is not a good idea let alone cost with relays etc.
Mind you those old merlin motors never seen to die... but that one is very old.
