Have you tried bitter apple, or is that just for dogs? Guess you just have to find something that he hates the smell of or put the cords away.
Can you wrap two non-insulated wires around the cord without them touching each other and hook them to a 9V battery? That much shouldn't hurt a cat but I'm no vet. Squirting them with water or yelling won't help, a cat will just come back when you're not there.
If you find a big non-chain electronics store, you can usually get a no-name generic version of a laptop power supply. They run a good deal cheaper than the OEM ones.