The BIOS contains an option for "Console Redirect". It is typically OFF by default. If you set it ON, then power cycle the system, the BIOS screen will appear on the attached terminal. Make sure to set the baud rate properly... it should be 9600.
Have you tried hooking a console to the serial port? On some BIOS versions, "Console Redirect" is set ON by default.
The kicker here, obviously, is that if the default for this option is OFF, you have to attach a graphics head to the graphics port of the system as well as a USB keyboard to get into the bios and set console redirect to ON. There is no getting away from the fact that these Galaxy class systems use PC motherboards, albeit ones beefed up for SUN's needs.
I have tried this and it does not work, when I power cycle the system I see the ILOM 's boot messages and not the main system bios. On the x4100 the console redirect has the following options : (in Advanced -> Remote Access Configuration )
Remote Access : Enable
Redirection After BIOS POST : Always (other options Disable, Boot Loader)
I have gone through the bios and these are the only options i have that seem relevent.
The system I have has the original bios and firmware on it.