How do I get to my rear speakers? Is the ring aroundthe outside of the speakers just snapped in? Or do I have to remove the entire package tray?

The mesh is not snapped in. If you pull it out, the pins holding them in will break. You could do this and then glue them back in after you replace the speakers.

 

Or, the "correct" way: Remove the bench part of the rear seat by undoing two bolts at the front of it and then unhooking it at the back. This gives access to the bolts holding in the backrest. This also needs to come out. Then you remove the plastic cladding that is bolted and snapped onto the C-pillar. These have the seatbelts passing through them, and you can just extend the belt and rest the plastic on the ground outside the car.

By now, the rear shelf should be possible to wiggle out.

 

Installation is the reverse of removal :-)