I did this way:
Flashed an SD Card with the latest Maverick image.
Flashed a second one with Debian-Armhf-3D image and made a tarball of its rootfs.
Placed the obtained tarball in the /home/oem folder of Maverick SD installer card and modified the oem-installer file accordingly.
Rebooted, but without success.
Booted again with Armhf-3D SD card to check out which kernel it ran:
$ uname -a
$ Linux efikamx-armhf.lan 18.104.22.168.25-efikamx #1 Wed Sep 21 22:16:42 EEST 2011 armv7l GNU/Linux
So the installer didn't place a uImage and uInitrd in the SSD bootfs for the 22.214.171.124.25-efikamx kernel.
I added them copiyng from SD Card bootfs:
# cp /mnt/mmcblk0p1/uImage-126.96.36.199.25-efikamx /mnt/sda1
# cp /mnt/mmcblkop1/uInitrd-188.8.131.52.25-efikamx /mnt/sda1
# ln -s uImage-184.108.40.206.25-efikamx uImage
# ln -s uInitrd-220.127.116.11.25-efikamx uInitrd
Now the SB booted fine and kernel boot messages appeared on screen, but I got a blank screen.
Got a shell with ALT+F1 to log in, but no luck.
It returns "login incorrect" with demo and root default passwords.
Sorry for the long post.