SOLVED
I discovered that if I put the config (both in the root and in \config) on my boot installer, which had the 64MB PFSENSE FAT32 partition, the ECL worked correctly.
So, I reformatted the USB drive I was working with as a 64MB FAT32 partition (named PFSENSE) and wala, success!
Previously, the USB drive was formatted to use the entire drive of 4 GB. No idea why reformatting it to a smaller size matters... But, in case anyone else runs across the same problem...