You have to in order to be able to use the i.MX31's internal boot rom. I think the errata says that the USB code is still broken so the serial port is the only way. I don't know if rev 2.0 fixed that. I wrote a brief description on how to do it, but it's almost too much work with tiny little parts to try without the right extraction tools:
http://www.logicpd.com/su...viewtopic.php?t=1178