First of all, if you're seeing the prompt ALC_DNLD> you're connected to the wrong device; that's not the NBX V3000, that's the Analog Line Card's prompt.
The V3000 unit itself (3C10600), at the Com1 port, should show a prompt of V3000>
Perhaps at the auction, you purchased not only the NBX V3000, but also a 3Com Gateway Chassis (3C10200), in which you have an Analog Line Card (3C10114)? If you connect to the Com1 port on the ALC, you will see a prompt of either ALC> (if the system if already functional) or ALC_DNLD> (if it's waiting to get its download instructions from the NCP)
Also, please verify...if it's a V3000, it's going to be a 1-U appliance, with an Ethernet port on the front, and (if it's American) 4 Line Card Ports, and 1 FXS Port. That's the stand-alone all-inclusive unit; includes call processor, voice mail, and the 4 Analog Ports (in Europe, they would be BRI ports).
I didn't know if what you had was actually an NBX100, with a separate Call Processor card at the top, and 6 card slots, all in one chassis.
If all the above is true, and you are connected to the V3000's Com1 port, and get a prompt of V3000> you should type a command of nbxIpConfig (paying attention to capitalization) and press Enter, and it will walk you through the elements of setting up the network settings for the NBX.
-j