cd /media/XXXX/
mkdir overlay
mount EnginePrime212.img overlay 
mount -t overlay -o rw,relatime,lowerdir=/usr,upperdir=/media/XXXX/overlay/overlayupper,workdir=/media/XXXX/overlay/overlaywork overlay /usr

#change product code , you can use mine and skip vi ( put it in your /media/XXXX/)
# cp "/sys/firmware/devicetree/base/inmusic,product-code" "/media/XXXX/inmusicproductcode" 
# vi "/media/XXXX/inmusicproductcode" , change ADA2 to JC16, save & quit. 

#Once changed, mount it like: 
mount -o bind "/media/XXXX/inmusicproductcode" "/sys/firmware/devicetree/base/inmusic,product-code"

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/qt/lib
export AIR_SCREEN_ROTATION=-90

Last assignments files are Akai_Pro_Force_Private_Device.qml and Akai_Pro_Force_Private_Assignments.qml
You can put it in /usr/Engine/AssignmentFiles/PresetAssignmentFiles/JC16/

Once done, go to /usr/Engine
and ./Engine to run prime.