Two choices...with a simple Y
Contact the maker of you're servo and see if they can wire a reversed servo and use it on that side...

The other and one I've used before. but looks real bad,
Put one servo low in the fuse tail and use the top of the arm to one elevator...set the other high in the fuse tail and come off the bottom of the servo arm..but is much easier with a reverser..and a whole lot less measuring, and fiddiling around.

Easier is to buy a Y harness with a servo reverser built into it..
(If you can't slave two channels together in you're radio..)


I hope I splaned this right for ya..