I take you have never been able to start the car. Do you have the key turned to the "on' position when you jump the starter???
There is a starter relay under the hood on the left side of the bay (passenger side) under the little "boot" shaped cover. Pull it and check it. Do you have an voltage/continuity tester? You need one.
There is also a IGN fuse (fusible link) under there as well, check it. It could also be the MTX clutch contact. Have someone depress the clutch while you check the relay. It should have power on both sides of the relay (with ign in the "ON" position). If you are getting power to both sides of the relay, you should have power at the magnetic switch (it is the cylinder shaped thing on the starter).
It could also be the "theft alarm starter relay". It is under the dash and from the diagram appears to be behind the radio area.
If he said he had to have the key in the "proper position" for it to start, the ignition switch could have been going bad and finally gone bad...??? just a guess.
This is what the manual says for troubleshooting tips for a starter that won't crank
*Check the starter. (you know it will crank so that is OK)
*Check for poor contact at battery terminals and starter (again you know it will crank so...)
*Check the clutch pedal switch
*Check the starter relay (under the hood on passenger side)
*Check theft starter relay (under the dash)
*Check key reminder switch (appears to be the switch at base of steering wheel)
note: I added the comments at ().
The last thing it "could" be is the ECU. I am including links to the stealth316 site. A guy named Jeff put the site together and it is awesome.
ECU code diagnostic
ECU removal
Console removal for theft relay
Stealth316 home
Check out this site. It has tons of information on it and diagrams, pics etc. It should help.
Let me know what you come up with. Good luck