Just thinking off the top of my head, but wouldn't cloning the MAC cause conflicts with the existing MAC on the network?

I've done something similar with cloning my iPhone MAC to get free WiFi access on my laptop using the free AT&T WiFi provided to iPhones.

But if what you're saying actually works, this seems like a dead simple way of getting free access. I already have Kismac installed, so I'll definitely try it. Thanks!