When there is no keyboard present, the C3000 switches to serial console on port1. Just hook it up to another box (Unix Workstation, PeeCee running Linux/Windoze, doesn't matter) with a serial "nullmodem" cable. Start a serial terminal (e.g. minicom on Unix/Linux, HyperTerminal on Windoze) and set it to 9600,8N1,hw (9600kbit, 8 bits, no parity, 1 stop bit, hardware flow control). Power the machine on and you should see the PROM messages.