SD boot + USB root Lakka for Raspberry Pi 4?

Is it possible, or has anyone successfully loaded the nightly Lakka build with Pi 4 support from a USB SSD using the older method of leaving bootcode.bin on the SD card and having the OS run off of the USB drive? Hopefully someone here knows what I’m talking about. It’s a older way of running a Pi image off of a USB drive that was used before they enable directly booting from a USB on the Pi 2 and 3. The Pi 4 still does not have USB boot functionality, so this would be the only option I’m aware of for running any image (including a Lakka image) off of a USB drive. People have got it working on Raspbian, so I tried the same method, but couldn’t get Lakka going. Maybe I did something wrong, or maybe there is something essentially different about Lakka that makes it either impossible to boot this way, or that I would need to set it up differently.