Per 05 FSM from Sir Sam's download (see section 19 beginning on pg 19-27). I suspect from above is best; unless you remove the engine skid plate you cannot get at it from underneath. NOTE pg 19-26 has a method for purging air from the system on a refill that involves a special tool. Someone else will have to weigh in as to whether or not you can use the simple old school method of loosely install the fluid feed line; fill the reservoir; let fluid start to leak from the feed line so that line is full of fluid; tighten the feed line; and then crank the engine and turn the wheel (don't hold at full lock) a bit from side to side to flush air out of the system. Post how it goes and any hints for future use.
Removal
(1) Siphon out as much power steering fluid as possible.
(2) Remove the engine cooling fan.
(3) Remove the fan shroud
(4) Remove the serpentine drive belt.
(5) Remove the three bolts (5) securing the pulley
(4) to the pump (2). (Fig. 5)
(6) Remove the power steering hoses (1). (Fig. 5)
(7) Remove the three bolts (3) securing the pump
(2) to the bracket. (Fig. 5)
(8) Remove the pump from the vehicle.
Reinstall
(1) Install the pump to the vehicle.
(2) Install the three bolts (3) securing the pump (2)
to the bracket. (Fig.
.(3) Install the power steering hoses (1). (Fig.
(4) Install the three bolts (5) securing the pulley
(4) to the pump (2). (Fig.
.(5) Install the serpentine belt.
(6) Install the fan shroud
(7) Install the engine cooling fan.
(8) Refill the power steering fluid and check for leaks.