Well, if your heart is set on that, you can always install one clevis above the arm and the other below.
Regardless, coated cables rubbing on their cross over points has never been a problem. If one uses bare steel cables, it might cause RFI so I would never use uncoated cables. Of course Kevlar eliminates any possibility for RFI and teflon coated kevlar is the slickest there is at fuse exits....I remove a small length of teflon coating when tying the knots and dripping ca on the knots. No need for ferrules
The biggest advantage to running nylon coated steel cables is the fact that connections to theaded rods or eyeloops becomes trivial. What we do (In Pattern circles) is to fold the nylon coated end over and run a match flame over the nylon insulation, remelting the nylon slightly. Many guys don't add any ferrules and swear that none are necessary but I always have (in the distant past when I used steel).