Well, if you take a look at the Chinook, you'll notice that it uses a hover locomotor with a prefered height which it'll use to fly at.
It also uses a special Taxxiing locomotor to allow it to lift upwards upon creation and to get down to the ground when unloading.
To make your plane hover like a chopper, give it a normal hover locomotor (chinook one should work fine for tests) and a taxiing locomotor to make it go up when you create it (I think it might also be used to reload).
That should at least work for testing purposes. Perhaps it may even be everything you need. Otherwise, you might get what you want by a little bit of editing...
