Unless you are wardriving on some one elses connection, the dynamic IP still references to your modems MAC Address in ARP with the ISP, so no matter how many times your change it, your ISP still tracks and ( allows internet ) via the MAC address reference. If you change your modem or MAC address by hacking the modem if the modem allows for cloning MACs or alteration, you will lose your internet until your ISP references the MAC to your account.
If you are a wardriver or internet cafe squatter.... it can only be tracked to the cafe's or parasite wardriving access. Only way to be annonymous then is to keep changing your MAC address in your laptop so that logs at the cafe's dont show your trail.
Best of all its best to be legal and avoid the sneakyness that can land your *censored* in a lot of trouble. IF they want to find you, they have ways of doing it no matter how well you cover your tracks, so its not worth it. The best hackers out there use annonymizers to avoid being tracked down the best that they can, and some even move to different hardware frequently to avoid being tracked at a lower hardware level.
For me personally I know of ways to be annonymous, but would never do anything to get into trouble... """ITS NOT WORTH IT"""