The kernel fails before starting the rc(8) script? If so, capturing information can be difficult. If the failing system has a serial port, the bootloader can be configured to use a serial console, and the failure can be captured with a second system and a null-modem cable. If there is no serial port, or the additional hardware is not available, the only recommendation I have is to photograph the display screen.
If the failure occurs after rc(8) has started, then perhaps booting in single-user mode may permit a shell to be started on the console. boot> -s is the command to the bootloader to start in single-user mode.
|