As Jeff mentioned, it is part of the hub assembly.
That said, it is pretty easy and straight forward. You will not have to grease them or anything like that as they are an internal component of the bearing itself.
A few years back I replaced a set on a Chevy for a customer that was an AVID off-roader and seemed to live in the water. So to help the life of his replacement bearings I drilled and tapped a hole and installed a Zerk fitting so he could grease them and push out the water that gets trapped in the bearing area.
I am sure the same can be done for the Trac as well.