Are the orthotics fitted by a podiatrist? Normally they give pretty strict instructions as to how to deal with these sorts of things.
Is it just a muscle injury, or do you have an actual fracture?
Shin splints are an overuse injury- if you are still using the =same muscles on the elliptical trainer, you will exacerbate the problem. But if you are on the road to recovery, the elliptical is great because it involves no impact.
Make sure that stretch and recovery are a major part of your routine, slowly introduce yourself back into running and walking any distances, and vary your cardio workout.