The aftermarket can help you, only catch is you'll have to find a shop that is competent at doing a little fabrication work. Here's a cable and install kit from Jegs that should fix you up. Where it attaches to the factory shifter will take a little fabbing up, but the trans end should be simple.
TCI 850800 TCI Morse Cables
TCI 704400 TCI Shifter Bracket & Lever Kit
The shop you talk to will probably want to get different stuff but this will get you headed in the right direction.
Of course you could go with an entire shifter kit and mount it in the floor! Won't be the first one I've seen fixed that way!