1. If you can use a ulock, I would highly suggest a ulock, cables have a reputation for being very easily cut. They do sell combination ulocks -
http://www.kryptonitelock.com/Outlet...=1000&pid=1106

2. If you want to use a cable combination lock, I would just use a regular cable -
http://www.kryptonitelock.com/Outlet...=1001&pid=1124

(They sell shorter versions of the same cable as well)

And a regular combination lock, anything like these -
http://www.amazon.com/Master-Lock-17...5663027&sr=8-3
http://www.amazon.com/Master-Lock-65...5663027&sr=8-5
http://www.amazon.com/Master-Lock-17...663027&sr=8-14

The cable locks with the combination built in always require twice as much cable and I find more annoying than a regular cable - you just loop the cable through itself on the thing you're locking it to, then wrap the end of the cable around a piece of the frame of the bike and lock it. It looks like like this:


People often think

3. If it was me personally, I would first go for the ulock. But if that's not possible (due to the way that you have to lock your bike up), *and* the thing you are locking it to is secure (no point in an very secure lock if they can just unscrew 2 screws and walk off with everything), I would personally consider getting a bike chain. I use the Kryptonite New York Noose -
http://www.kryptonitelock.com/Outlet...=1002&pid=1196

That's what I use for locking up my bike when it's in my car but sitting in a parking lot, or when it's on my bike rack. Though this would still require getting a combination padlock as well.