1) Include llshell.inc in your northbridge Config file
2) In raminit.inc (or whatever), make a jmp out to low_level_shell, setting
   a return label in %esp.
For example:
ram_set_registers:

	mov $llshell_ret1,%esp
	jmp low_level_shell
llshell_ret1:

        /* Disable and invalidate the cache */
        invd
        mov %cr0, %eax
        ....
3) Optionally, comment out two lines in ramtest.inc:
5:
        CONSOLE_INFO_TX_STRING($rt_toomany)
        // post_code(0xf1)
        // jmp  .Lhlt
otherwise, a ramtest failure will hang

4) build and flash as normal
If it worked, the speaker will beep, and you'll get a shell.
Type help or ? at the prompt for a list of commands.