hmm, if you have a spare null modem cable handy, plug it between ttyS0 and ttyS1, put the following line in your /etc/inittab
S1:2345:respawn:/sbin/agetty 19200 vt100
then type 'init q'
and then make sure minicom is set for those settings then with minicom in one console, type killall agetty in another and you should get a prompt
ok, shoot me that's overly complex
hit ctl ctl-A Z to find the settings and make sure baud rate, stop bits, etc... match on both devices