This is how I did it:
I have the Saitek Yoke and Throttle Quadrant, and an extra Throttle Quadrant.
My levers are set to:
Speedbrakes (reverse)
Throttle 1
Throttle 2
Prop 1
Prop 2
(none, I use a plugin that translates the full range of the lever to flaps detents in the plane)
My toggle switches at lever 4 and 5 are set to
4UP sim/starters/engage_starter_1
4DN sim/engines/mixture_max
5UP sim/starters/engage_starter_2
5DN sim/engines/mixture_min
To start my engines, I begin with pressing 4DN to set both prop levers to "START&FEATHER". I THEN turn both Ignition switches to NORM AND flip the Select switch to "2". I can now start engine 2 by pressing 5UP, and I haven't touched my throttle levers yet, they are at DISC. When engine 2 has stabilized, I flip the Select Switch to "1" and press 4UP to start engine 1, again without having to touch my throttle.
To shut off the engines, I press 5DN.