That manual for the F-22 explains this, and gives you 3 options.

[ul][*]Option One - Use standard servos and program a computer radio for flaps so that the servos move opposite each other.[*]Option Two - Use a reversering Y-harness to connect 2 servos to the flap channel.[*]Option Three - Use a JR ST47 standard sport servo and a JR ST47 reversed sport servo connected to a Y-harness plugged into the flap channel.
[/ul]

Ken