I've taken the drivers seat apart several times. Once in my '93 850 and several times in my '96. The cable apparently wears until it's too short, but the replacement sure looked identical.

Take the seat out of the car so that you can devour it in comfort. Pop the trim at the hinge off. Unhook the upholstery from the teeth. Clip the hogrings, unthread the lumbar support knob. Worry the upholstery up to access what you need to. You may find you need to clip the hogrings on the intermediate upholstery retainers, but they're a pain to reassemble. And don't try hogrings w/o the special pliers. The last time, I found I could remove the motor, drop it down and change the cable w/o messing with the intermediates: very satisfactory. One post I read said to use wire ties instead of hogrings. You'd be working to pass 'em under what you need to on the intermediates but give it a try!