Use a glow ignitor with an attachment for alligator clips. I use these:
Put a rechargeable AA battery (I like Turnigy LSD's, Eneloops or Energizers) into the glow plug starter and you're good to go. Plug it into the 'glowplug' end of the wiring assembly and strip the ends and crimp on alligator clips. Attach clips to Cox engine, go for your life.
Never use an electric starter on these engines, way too easy to hydrolock them.
Cheers - boingk