How to go about repairing broken/cracked plastic steering?

You need to strip the wheel down first,take off anything you dont want epoxy or filler on.Give it a super good cleaning with thinner or some kind of chemical cleaner that wont melt the plastic.Get some epoxy that comes in a syringe for easy dispensing.Rough up the repair area's with 36 or 40 grit . Clamp the pieces in place and open the cracks up enough to get a good amount of epoxy in and fill in the cracks with epoxy. Make sure to drill the ends of any cracks out with a small bit,this will prevent the crack from spreading. Use a high strength filler for the first application,something like kitty hair (fibreglass strand filler). Then finish with glaze,primer and paint.Done right it will look like new!

Or find another wheel..