Mixture control with the keyboard:
CTRL + SHIFT + F1 - idle cut off
CTRL + SHIFT + F2 - decrease mixture
CTRL + SHIFT + F3 - increase mixture
CTRL + SHIFT + F4 - fully rich
Just using F1,F2,F3,F4 will control the throttle; CTRL + same function keys will control prop. By default, all engines are controlled.