You can replace it through the passenger side without having to take out the ring and pinion and carrier but you have to be creative.
-Take off the wheel/tire
-remove the caliper
-remove the rotor
-remove the hub assembly
-pull the axle shafts out of the passenger side
-pull off the CAD plate
From the knuckle opening on the passneger side, use a long rod, or put together a bunch of socket extensions, and feed them through the knuckle and into the axle tube. Make sure your extensions or rod is up against the seal and then just tap out the seal. It will fall into the CAD housing.
To get the new seal in:
-Take a 4ft peice of all thread and feed it through the knuckle and axle tube until it gets into the CAD housing.
-Slide the new seal over the all thread
-Slide a socket over the all thread that matches the diameter of the seal. (This socket will be what drives the new seal in place so make sure you pick out the perfect size for it.)
-slide a large washer over the all thread to butt up against the end of the socket
-thread a nut on the end of the all thread to hold the socket in place.
On the knuckle side of the all thread:
-Slide a large socket over the all thread
-Slide a large washer over the all thread
-Thread a nut onto the all thread
Then have someone line up the new seal in the axle housing and firmly hold the drive socket and end of the all thread in place. The person on the knuckle side can now begin to slide the large socket into the large washer in sort of a make shift slide hammer procedure.
Stop often and recheck your progress and make sure the seal is going in straight.
After you get the seal driven into place, take off the nut on the CAD end and pull the all thread back through the axle tube.
When you reinstall the axle shaft, be sure you feed it into the tube straight. If you dip it down into the tube, you can pick up some of the nasty debis that collects in the tube and if you get that caught in the seal, it can leak. Also if you don't feed the axle in straight, you can inadvertently bump into the seal you just installed and either totaly or partially dislodge it which again will cause a leak.
Here is a pic of the orientation the seal should be installed in:
Good luck with the whole thing, if you just take your time, you should be able to get it done in about 4-5 hours. Hope you get it fixed soon !