If you're able to ping the old address (probably when connected to your current network?), why not run the jetadmin then? Or simply use your browser to connect to the web interface, or use telnet if that's enabled. There's no need to connect it to your machine using a crossover if you can already ping it - just log on, do the configuration changes and apply them.. and start using the box using the new address you just defined.
There's no point making things any more difficult than they have to. =)
