The simplest way to connect both flaps to one servo is to set up as if you were doing ailerons, using a torque rod set up like this:

http://www3.towerhobbies.com/cgi-bin...LXD946&P=7

Doing this requires that the trailing edge be cut along the hinge line, install the torque rod and reglue the trailing edge back on to the wing. Since this will degrade the structural integrity of the trailing edge, it would be a good idea to reposition the wing hold down bolts to a position forward of the cut portion. Then install the flap servo in the wing center section. Simple.