I too have had to make a temporary Run, but I used...
3/8" Nylon Rope
http://www.homedepot.com/Tools-Hardw...atalogId=10053

and used a Pulley/Trolley to connect the leash to...
http://www.homedepot.com/Tools-Hardw...atalogId=10053

I had two trees that were well apart, and this gave him a nice run.
And yes, I had to untangle him from the far tree several times, till he sorta learned not to wind himself around it.

After all, the Rope came in handy for other purposes, which is why I'd recommend it, rather than a Cable.

Have a good Day !
S.W.