What happens when you boot the eMMC flasher?

So, trying to re-flash Angstrom onto my eMMC. I downloaded the eMMC flasher image, put it on a card and booted from it. Thus far, I believe I have followed the agenda perfectly.

I was presented with a login prompt, so I logged in as root. Nothing happened except a command prompt.

So I did some more googling, and found this page: http://www.crashcourse.ca/wiki/index.php/BBB_software_update_process

And I went and executed /usr/bin/emmc.sh. the script is currently executing, but it’s getting a lot of error messages of the “tar: can’t make dir” and “/media/1: device is busy” type, so I’m fairly certain that in spite of the ongoing frenetic blinking of the onboard LEDs, I am not going to come out the other end of this script with a working BBB.

I can boot from a regular angstrom SD card without a problem, but I want to be able to boot without holding down the user button. what am I doing wrong?