Anti Cable Slip?

[MichaelBick]

You could look into sailing line and tying a bowline at each end.

[GeeTwo]

You could drill a hole through a rotating bolt, pass the cable through and secure with crimps or clamps, either a single block behind the bolt, or loop the bitter end back around for a standard loop crimp.
Another possibility would be to crimp a loop snugly around a pulley or other sheave (e.g. two shaft collars with a gap between them).

[Collin Stiers]

I believe you are referring to a way to make sure you don't slip back down the rope after you climb. if you are using rope (I recommend military 550 chord , also known as Para-chord) then there are a few options available.
1) a knot, the types of knots you want are either a prussic knot or a taught-line hitch. These are both knots that can slide along rope but lock in place under a load.

2) a repell and belay system, this is used a lot to get people down from high places SLOWLY, but the system provides a way to stop the decent simply by changing the angle of the rope into the belay system.

3) commercialy available rock climbing equipment can do something like this.

4) a ratchet system. you spool that you attach your rope to cannot be back driven if you put a ratchet system. most store bought winches has a locking ratchet on them