Not sure if this has been added or not, but we have a map available in all the visitor centers and the climbing information center that shows the bearings and route to Camp Muir. You can d/l it here: http://www.nps.gov/mora/climb/images/mapcompass.pdf
And I also agree that the hike to Muir is a great one. Just be prepared. Also, don't be like the individual I saw the other day... no sunscreen, sunglasses, water, food, boots (was wearing tennis shoes)... he was picking up each leg to continue on. *sighs*
Ah, the things you see when you work here.
Anyway, enjoy the hike! It's a great one and I highly recommend it.