If you have the key for the system, you can reset the ILOM to it's default password. I'm not exactly sure of the process, but you will be able to find it on the Oracle site. From memory I think you have to hold the key in the engineering position while the system is power cycled, you'll then have around 60 seconds with the default login.
But to be certain you should check the documentation so as not to waste time.
I don't think the password reset works like that (as there is no ILOM; and even on ILOM machines it does not work like that). The process is a little more complicated. The M-Series (3000 to 9000) server can make use of the key to login as default user.
I have to look up the right procedure to reset the password. Also the only way to power on the domains is via the setkeyswitch command from SC. The keyswitch on the frontpanel will only power on the RTS (redundant transfer switch) in the bottom of the rack... If you still have a valid service contract, open a service request to get the password resetet.
You are right, I was thinking of the M3-9000 series. I've checked my old notes on the Enterprise series last night on this and the process is more complex.
You have to interupt the POST with a hard reset on the card as it displays the Sun copy right message and then "Control-A"" the unit should just display a blank prompt ">" I think.
Once here you have to run the "getbootflags" command and then the "setbootflags" to disable auto boot. Then you have to "Control-X" - then there are a string of commands to reload and reset the local Java paths and .jar files.
The sequence is always the same, however depending in the firmware the commands are different.
As to doing this without support from Oracle, unless you have done it before - I'd call them in to help.