Get yourself a windows pc, configure Hyperterminal to "autodetect
speed" and connect the laptop to the serial port on the backside (there
aren't many, so you should be able to get it right irrespective of what
the manual says).
That will give you access to the servicve processor menu on bootup. The
service processor loads the aix kernel and that becomes your console
too.
If you use minicom, pl. set speed to 19200 (if 9600 bps doesn't work).
BTW -make sure your laptop is connected to powersupply and doesn't
powerdown when installing. AIX is not too good at resuming the
installation process.

regards
-kamal