Answering my own question...
I connected a TTL serial cable to the console pins and found the device could be identified and read by the firmware, but the CLI "ls" command showed no contents other than a dummy config.ini file.
It turns out that the Romulator's filesystem code does not like partitions. So, I used the following Linux commands to overwrite the partition table, format, and label the device:
Code:
mkdosfs -F 32 -I /dev/sdb
dosfslabel /dev/sdb Kickstart
This solved my problem. Now I get a list of ROM images and can select and start any of them. The Romulator is an awesome upgrade to my computer. Thank you very much for creating something so cool!