It should be simple enough to wire up a glow plug relay so they come on automatically. Glow plug continue to heat after the light has normally gone out. I just wired ours up with a proper fuse rated at 30 amps and it's fine BTW.
On plant machinery the ignition switch has 2 start positions, the operator turns on the glowplugs rather like we turn on the starter, then the next position turns the starter, both positions are spring-loaded.