trying to boot Android using USB

Hi all,
I'm trying to use my USB flash drive to boot Android using my
Beagleboard-xM, Rev C.
I've been going through all the website and cannot find any specific
direction to do this process.
I've tried doing the one on the wiki for FroYo but with Gingerbread
image, but it did not work.
Does anybody know how should I achieve this process in an orderly
Thanks in advance.

Sorry, this only loads kernel to the RAM and boots.
I'm looking for a way to use USB as my 'rootfs' when running Android.
e.g.) setenv bootargs root=/dev/sda1
The above statement does not work of course.
Seems like no ones' done this on the beagleboard.
any suggestion on modifying boot sequence then?