How to create a SD card for BeagleBoard xM without using Narcisus?

Hi all. I am quite newbie to this stuff - embedded linux, beagleboards and all.
I was able to generate an angstron build from Narcisus and get it running, according to this tutorial:
http://treyweaver.blogspot.com.br/2010/10/installing-angstrom-on-beagleboard-xm.html

When trying to use something else the narcisus builds, the boot fails to work.
I’ve tried the following:

In both cases, I took the following steps:

  • Set up the card, using omap3-mkcard.sh
  • Copied MLO, uImage and u-boot.img, in this order
  • Uncompressed the rootfs image, systemd-image, to the second partition
  • Uncompressed the module image, modules-beagleboard, to the second partition
  • umount both partitions
  • Tried to boot from beagleboard xM, both unsuccessfully.

So, I ask you: what am i doing wrong?

Thanks in advance!
Paulo Sherring.