How do I find my ethernet address (HostID) under OS X in the terminal?

This site will do the trick give a try..
http://www.uark.edu/compserv/network...ipaddress.html
Post back if it really doesnt help

Dimyas, launch the System Preferences application from the Apple menu and click on the "Sharing" pane; the IP address currently assigned to the machine you're on will be displayed toward the bottom of the window in the middle. If you are fortunate to have a static IP address, write it down and you'll always have it. If you IP address is dynamically assigned, it will change every time you close and reopen your IP connection. With a modem, this is every time you dial in. If you have broadband, it's every time you unplug your cable modem/DSL router/whatever, so, if you want to maintain the same IP address, just don't unplug your broadband device; it will give you the same IP address every time you restart your computer as long as the broadband device itself is left on.