In reply to thebigfriendlymoose: That looks like normal 60cm slings, the OP asked for runners made from 120cm slings.
I've carried one of these in winter before, just doing exactly the same as you would with a 60cm sling for an "alpine quickdraw" but doing it with a 120cm sling. I suppose it's kind of pointless really as it's just as easy to grab a sling and stick another wire gate on it but if you're on easy ground or long wantering routes it can be a convenient way of carrying them.
Once you've trippled them up they're pretty long though so what I do is usually twist them up like you would twist a sling for storage then clip the carabiners together. It's quite hard to explain but basically put a finger in each carabiner and twist them in opposite directions till it's tightly twisted enough that you can clip one of the carabiners into the other and it'll sit in a neat bundle.
It does mean you'll fall slightly further obviously but it's the sort of thing you'd use on a 40-50m winding route you're comfortable on. I wouldn't worry about extending something with a 60cm sling though, you're only going to fall another 40cm, which is pretty insignificant unless you're cragging and near the ground already. Better to run the risk of falling an extra wee bit than to get pulled off by rope drag near the top.
Ben