Create a black and white texture to be used as the interlace.
(I did this in blender with a texture on a plane, but it can be done with any image creation program)
Then use that image as a factor to combine different versions of the base image, that have been distressed with different filters.
(Click on the image to enlarge)
If you animate the values for the distortion filters or animate an inversion of the interlace texture you can maybe emulate NTSC in all of its glorious ugliness...