Hi,
I have one of these on my S&S coupled bike for the rear brake
Thorn-Cable-connector-for-bare-inner-wire-BRAKE-ONLY-Black

There is also a gear cable version
Thorn-Cable-connector-for-bare-inner-wire-GEAR-Black

Once fitted to a bare run of inner cable, they can be used to split and rejoin the cable as often as you wish.

I suspect you just need cable cutters and a small allen key to fit them to your cable inners.

I hope this helps.