Yes the original ones should be fine as long as they are long enough, they are very flexible too.
I changed mine because I found they used aluminum leads rather then copper = WTF? but it didn't change the sound, the main cable did tame the highs a little bit and reduce sibilance, but the difference is small.
I recommend Mogami 2893 wire, and I'm not the only one who find this cable to be good with K240's, very cheap for what you get, Teflon insulated and durable.
It's stiff and thick, but if you strip it down and take out the internal wires, braid them and pull them through some nylon shoelace or similar, the result will be a very good, fairly flexible cable, with good microphonics.
For strain relief I recommend adhesive heat shrink and cable binders.
It takes a while to make a good cable, but it's well worth the effort.
If you feel brave you can make a Y split cable for dual entry, and then solder the cables directly on to the drivers, in theory this should be better, I have tried it, but honestly it's not worth the trouble.