Adding s-video to older tv?

I have an older mitsubishi tv that I really like but the only inputs that it has are coax and composite, It would be really sweet to add an svideo input to this. If I under stand correctly when the composite signal comes in is goes through the comb filter and is split back into Luma/Chroma, so would it be possible to trace the inputs to the comb filter and attach a svideo port after the comb filter? Is this really possible or am I just hoping?