You need to build barebox with
make ARCH=arm imx_v7_defconfig
make ARCH=arm
Or you can do a 'make ARCH=arm menuconfig' and disable other imx boards that will be built by default.
This will produce an 'images/barebox-freescale-imx6q-embedsky-e9.img'
copy it to SD card with
dd if=images/barebox-freescale-imx6q-embedsky-e9.img of=</dev/sdcard> bs=1k seek=1 skip=1
Make 2 partitions on SD
First is bootfs, second is rootfs
You should put zImage and DTB to bootfs, default filenames are 'zImage' and 'imx6q-embedsky-e9.dtb'
You can drop in barebox shell and edit boot scripts if needed, they are in /env/boot/* files
Default is mmc1 or mmc3, depends on boot media.
Edit it with command 'edit /env/boot/mmc1' and save with 'saveenv'
Other usage examples are in barebox documentation.
Look at my github tree at apxii/linux · GitHub
But it is mainline-based, and DTS will not fit in Freescale tree.