Ok, So I'm pretty sure I've gotten the problem solved with my EMMC module on my XU4.
You will need 3 things to make this a success.
1. UART Module available from hardkernel or ameridroid (USA), or you can just buy an ftdi usb to uart cable but make sure you buy the 1.8V version so you don't over-voltage the console port
2. MicroSD card flashed with the latest version of Armbian I used 5.25
3. EMMC module for the XU4 ALSO flashed with the lastest Armbian version.
A. Install BOTH the microsd and the emmc module into the XU4
B. Hook up the uart module to another computer and open up putty or hyperterminal or whatever you prefer, so when you power up your XU4 you can see the boot process (baud rate is 115200)
C. Switch the Boot selector switch to microSD card.
D. Apply power to XU4
E. After you see text scrolling hit enter twice to stop UBOOT
F. If done correctly you should be greeted with a 'Exynos5422 #' prompt
G. Run this command "run copy_uboot_sd2emmc"
H. Below is a printout of a successful copy of armbians uboot to the special-hidden uboot partition on the EMMC module
Exynos5422 # run copy_uboot_sd2emmc
reading FWBL1 ..device 0 Start 1, Count 30
MMC read: dev # 0, block # 1, count 30 ... 30 blocks read: OK
completed
eMMC OPEN Success.!!
!!!Notice!!!
!You must close eMMC boot Partition after all image writing!
!eMMC boot partition has continuity at image writing time.!
!So, Do not close boot partition, Before, all images is written.!
writing FWBL1 ..device 1 Start 0, Count 30
MMC write: dev # 1, block # 0, count 30 ... 30 blocks write: OK
completed
eMMC CLOSE Success.!!
reading BL2 ..device 0 Start 31, Count 32
MMC read: dev # 0, block # 31, count 32 ... 32 blocks read: OK
completed
eMMC OPEN Success.!!
!!!Notice!!!
!You must close eMMC boot Partition after all image writing!
!eMMC boot partition has continuity at image writing time.!
!So, Do not close boot partition, Before, all images is written.!
writing BL2 ..device 1 Start 30, Count 32
MMC write: dev # 1, block # 30, count 32 ... 32 blocks write: OK
completed
eMMC CLOSE Success.!!
reading bootloader..device 0 Start 63, Count 656
MMC read: dev # 0, block # 63, count 656 ... 656 blocks read: OK
completed
eMMC OPEN Success.!!
!!!Notice!!!
!You must close eMMC boot Partition after all image writing!
!eMMC boot partition has continuity at image writing time.!
!So, Do not close boot partition, Before, all images is written.!
writing bootloader..device 1 Start 62, Count 656
MMC write: dev # 1, block # 62, count 656 ... 656 blocks write: OK
completed
eMMC CLOSE Success.!!
reading 0 TrustZone S/W.. Start 719, Count 512
MMC read: dev # 0, block # 719, count 512 ... 512 blocks read: OK
completed
eMMC OPEN Success.!!
!!!Notice!!!
!You must close eMMC boot Partition after all image writing!
!eMMC boot partition has continuity at image writing time.!
!So, Do not close boot partition, Before, all images is written.!
writing 1 TrustZone S/W.. Start 718, Count 512
MMC write: dev # 1, block # 718, count 512 ... 512 blocks write: OK
completed
eMMC CLOSE Success.!!
if you receive a eMMC OPEN Failed.!! message you didn't select the microSD as the boot
Final step is to remove power, remove the microSD card and move the boot selector switch to the EMMC module.