Boot other rk356x img on CM3 (RPi CM4 IO board)

If I go to and download EmuELEC-RK356x.aarch64-4.6-TEST-07082022-rk356x.img.gz, how can I get it to boot on my CM3 + RPi CM4 IO board?

I can flash it to the eMMC using rkdeveloptool, but it won’t boot. What are the next steps? Is there a new dtb that I need to add/enable? Is there a Radxa Wiki that describes any of this?