Well, to make it function, first you'd need some way (scripting?) to output the tracking factor (time in reticle x distance from center of reticle per ship on screen, then take the largest) to a number. Then you'd need to dynamically link the number to the homing ability of that warhead launch. This would be pretty cool; an analog homing system, instead of the aspect seeking digital system.
This number could be rendered on screen as 'tracking strength' as either a number, or a gauge onscreen. Once you have feedback the SCP would have to work out dynamic pitch variation for sound effects (which could also lead to 3D doppler effects in the future) then apply that to the heat-seeking droning sound.
It's a lot of work, but every part of it would be neat.