Always a suggestion.... :
This is a quick guess mind you...25 ton winch...with a 30mm wire cable...correct?
This puts the cable at about 1.18" which is just shy of 1 1/8" which covert to .8mm or around 1/16" of an inch!
In the 1/35 scale world.
OK..with that two quick options....
Make your own using really fine lamp cord wire...24, 26, 28 gauge. 3 or four wires wound concentrically around each other. I you take the three or 4 wires and secure them to your bench/vice better if you have them secured in this configuration:
X
X X
X
....do not wind yet....place the other ends in your variable speed drill. If you stick a pencil with the eraser rounded in between the wires on the drill side, pull taught (the wires) and turn the drill on SLOW (hence the variable speed) slowly wind the wires while pulling the eraser towards the secured section on the bench at around the same rate your drill is running. Slower is better....too fast and it can bind an even break. Actually much easier than it sounds...trust me.
Option II - This depends on the length needed but, go to The Armor Farm site...
http://armorfarm.com/product-category/accessories/ They have two cables in the package. These are 10" long...thinking that might be enough? :
These are ultra flexible. Will wind around any cable drum with ease I think. If they are too thick as I think these are around 1/8" in diameter....counter-wind the cable and carefully remove one wire or two or even 3...there is seven in each cable (real easy to do) and then wind back together....best option.
Picture of the unwound cable....
This is worth a shot.....if you like I can give this a shot today and show that it can be done...........give me a guess on the length needed and if you happen to have the spec on the cable thickness, just to be sure this is about 1 1/8" in real life~!!
;D