If you have flaps on a switch, and have two positions, takeoff and landing, it's actually easier than you think to add elevator compensation.

Go into the pmixes and set a mix with flap as master and elevator as slave. Turn the mix on, but leave the switch as NULL. Put the switch in the takeoff position. Select the rate (A or B) and then adjust the percentage until the elevator moves where you want it. Do the same thing when the switch is in the landing position.

If you have a slider activating the flaps, do the same thing, but select Spline as the curve. You can now set a variety of points for the amount of elevator you get with deployment of flaps.