If you use 2nd gen QuadCab seats... you can only use 2000 and up. 99 seatbelt equipped seats used electric solonoids to control lockup. You would have no way to control the function of them without the corresponding black box under the seat (actually an electronic box with a device that measures tilt, G-force etc). And that box is tied into the ignition, domelamps and the airbag control module. An impossibility. Unless your able to flip a rigged up switch right before the moment of impact.
Dodge did away with this complex, problem plagued setup in 2000 by going with a simple mechanical lockup device in the seats themselves instead of electronic solonoids. I had a 99 with these... and they used to mess up all the time and cause power to be supplied to the solonoids all the time and kill my batteries if it sat for 3 days. Was a real pain to fix using a factory manual. Dealer was clueless on what to do. I had to change the wiring so the solonoids were only powered up (unlocked to pull the belt out) if the key was on. Normally the are unpowered (locked) when the truck is off... when the door is opened and the dome light comes on... they power up and unlock so you can put your belts on before starting.