My opinion, having done it for a freind's 1/4 scale Cub.. don't bother.

Weight of motor to start engine (big - required to move piston past compression).
Linkages / powertrain to connect motor to engine. Also need a support to hold motor.
Batteries to power said motor (again, big - need quite a few electrons to power that motor!)
and one channel & servo to turn on switch.

For anything less than a 90 sized plane. Over kill. over weight.

And the charge in the 4 'c' cells only allowed for about 3 or 4 starts.

You still need a metod of 'igniting' the glow plug, and priming the engine...