Yes you can do this, but without a donor car for the necessary parts the cost would be astronomical. My advice is to forget doing this and sell the A/T car and buy one with a manual if that is what you want.
Junkyard
auto trans fluid its crazy i know
how do i fill my trans fluid in 1996 nissan 200sx 1.6 l manuel trans
I believe that is a Tremec T45
On the upper side of the transmission.
it tells you in the manual. I have a '96 tercel 2 door manual trans. and I do believe the gas tank capacity is 47 litres.
On top of the trans close to the firewall and engine block. Look where the shift cables (manual trans) come out of the firewall.
little over 2400lbs in manual and almost 2500 in auto
Valvoline gear oil 80W-90
Pick up a Haynes repair manual for the vehicle. They have wiring schematics in them.
In a 1996 Ford Ranger : The 5 speed manual transmission takes ( 2.65 litres / 2.8 U.S. quarts of MERCON automatic transmission fluid )
You replace the valve seals on a 1996 Saturn SL1 by removing all of the hardware to get to the valves, unseating them, cleaning them, and sliding the new valve gaskets on. In order to do this you should consider getting a good Chiltons or other repair manual for your make, model, year, and engine.