Download the GoFlex Home u-boot from this thread:
http://forum.doozan.com/read.php?3,12381
And use serial console to boot with UART method (kwboot) as described in this thread:
http://forum.doozan.com/read.php?3,7852,7852
Stop at the u-boot countdown, plug in your Arch rootfs USB. And boot! Come back here if you have problem booting into Arch or see errors.
http://forum.doozan.com/read.php?3,12381
And use serial console to boot with UART method (kwboot) as described in this thread:
http://forum.doozan.com/read.php?3,7852,7852
Stop at the u-boot countdown, plug in your Arch rootfs USB. And boot! Come back here if you have problem booting into Arch or see errors.