I set up two "virtual axes," one for engine one throttle and one for engine two throttle. Then I wrote a script that assigns each of the virtual axes (e.g., cms.a1 and cms.a2) the input from the actual physical throttle, multiplied by a factor between 1 and 0, depending upon the x-axis deflection of the microstick away from the center position. In the Control Manager GUI, I assigned the two virtual axes to Control Manager Device 2 axis U and V, respectively. Then, inside of AH's joystick selection screen, I simply mapped those two DirectX axes to throttle 1 and throttle 2.
If you like, I can post a link so you can download my map and script files and check it out.