O que você está procurando é chamado de Baluns :
For Distributing Audio/Video Via Cat5 Cable
Today's A/V industry has created the need to send high resolution audio and video signals over increasingly long distances of cable. However, the size and cost of the video cabling, especially when long lengths are involved, had created a challenge. As needs and technology change, future cable replacement can be quite costly.
A solution has been developed to tackle this problem. By placing "balun" adaptors at each end, signals can be adapted to be effectively sent over long distances of Cat5 cable.
eu encontrei uma empresa que tem uma página do produto completa.
Uma das fotos do produto tem esse esquema no dispositivo real:
Então você pode roubar seus pinouts e usar isso.