Probably known, but I played with the config file for the Warthog HOTAS in order to start and stop the Su-25T engines like the A-10C engines. With these two simple changes, it works :
{combos = {{key = "JOY_BTN30"}, }, up = iCommandLeftEngineStart, down = iCommandLeftEngineStop, name = "Engine Left Start", category = "Systems"},
{combos = {{key = "JOY_BTN29"}, }, up = iCommandRightEngineStart, down = iCommandRightEngineStop, name = "Engine Right Start", category = "Systems"},
:)