I created a bootloader patch that will make booting LE from eMMC on LePotato possible in 9.x builds - this will probably be also available in @adamg's new build.
For 8.2.x builds, you can try using installtointernal command if you still have Android on eMMC.
If I insert the eMMC card, it will boot from that. Do you happen to know how to boot from SD Card, when the eMMC is mounted on the board?