I used an old 8 channel JR 388s Tx. I forgot to write that each elevator half was connected to different channels as well. In that way I could use "tailevator" mixing, i.e., the elevators works together as ailerons as well as elevators. FYI, that is a waste of channels as it provides very little extra aileron authority.

I dont know about your Hitec, but probably there are a couple of pre-defined mixers for elevator-flap mixing and perhaps crow mixing that you can use together with Y-cables. IMHO the most essential mix with the SSE is the elevator-flap one, i.e., when the elevator goes up the flaps move down and vice versa. Anyting extra is the icing on the cake :-).

Sadly my SSE is no more. I had a serious case of brain-fade that caused its demise. However, I have a new kit waiting to be built ASAP.