Changing player vertical direction

[wok 1]

I love the ShackTac littlebird enhancements mod, specially the feature that lets you shoot from the skid positions. I was thinking how far I could get trying to do something like that but with scripts only, I quickly come to a stop. What I did is, I attached the player to the heli, but since attaching a player to an object disables the mouse movements I was looking for a way to overcome that, this is what I got (I put all the code in the EH so I can test it directly on the debug console.):

player attachTo[theHeli, [-1.11182,1.30444,-1.00752]];
(findDisplay 46) displayAddEventHandler ["MouseMoving", "if( _this select 1 < 0 ) then { player setDir ((getDir player)-1); } else { player setDir ((getDir player)+1); };"];

That lets you move on the horizontal axis (needs lots of improvements like limits for the movement, but kinda works).

I couldn't find anyway to do this for the vertical axis. I don't think there's any command that will let you do this. Does anyone knows a workaround to achieve this?