Switch for TCC lock up?

[AZ86B2]

I was wondering about the difficulty of adding a switch that would allow me to manually lock the TCC. Where would I need to tap into the wiring and do I need to have a fuse in the line somewhere? Main reason I want to do this is for better engine braking when off road... I wouldn't be using it on the street.
BTW.. vehicle is 93 Exploder w/ A4LD 4x4 (new, not in sig)
Thanks for any insight/info.