I don't have a write-up on it, but it's really easy..
Remove the trim bit below the glovebox (above the passenger footwell). The fan is just behind the glovebox, held in by three screws (torx if I recall correctly). Unplug the wiring harness and pull the three screws and it drops right out. Mine had a bit of dust/fluff in it I assume was throwing the balance off, because once I cleaned it out and re-assembled everything the noise went away.
A quick search found these:
Rosin Core Solder: Replacing the HVAC Blower Motor in 2005 Jeep Grand Cherokee
How To Remove Blower Motor 05+ WK
I kicked it out in under 30 minutes