Error: Unable to find device node for /dev/ad4s1b in /dev !

Greetings, FreeBSD Forums:

I have an iMac on which I've managed to install a variety of Linux distributions successfully, including Ubuntu, Linux Mint, and Mandriva. Recently I've become interested in the BSD side of things, so I decided to install FreeBSD. I burned the 8.1 i386 ISO to a DVD and booted up. The installation seemed to go well (I used all the defaults by pressing A) until I clicked the final 'Install' button.

I received the error

I rebooted several times to try again, but to no avail. What could have gone wrong?

if you can get to a loader prompt and
kdload the following
geom_mbr.ko
geom_label.ko
geom_bsd.ko
(I've forgotten how, see other threads mentioning
all three of those).
Then the install *might* proceed. Alternately,
use a 7.x install cdr, and in the "options" choose
an 8.x release (get the
default name from the 8.1 cdr?) from a server if you can input the
connection details somehow. Other workarounds...
Not in any position to write a guide though.
see other threads maybe.