Been a long time but this in generally it.
remove the back seat
You will see a round "disk" in the middle. It's under there, you just need to use a screw driver and gently pry the disk up, it's just held in with black sticky goop.
Remove all the connectors and hoses from the top of the fuel tank acces panel (round thing). (on the hoses there is a orange clip holding them on, be carefull not to loose the clip, they like to fly)
Unbolt the access panel round top of the gas tank, and pull the whole unit with pump out.
Swap the pumps and then reinstall.
'00 MR2 Spyder (extremely moded)
'00 GT-S Carbon Blue, Gone but not forgotten