The HP utilities for configuring JetDirect 600N (as used in LaserJet 2100 and others) only run under Windows. The web based configuration utility is not supported on Macs. However, once the DHCP assigned IP address is known (print a test page), you can use telnet to set the IP address and other settings. To access the printer:
telnet 198.162.0.5
Then, to see the current settings:
/
For help:
?
And then, for example, to set the IP address:
ip:192.168.0.100
Hope this helps!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040209155230870