Dual booting so flashing HDMU will not affect SPARK and if you install and use the E2 upgrade plugin in SPARK flashing a E2 image is very easy. But remember you still need to do the power off press ok button power on routine to select which os you want to boot in to.
I've uploaded pauldb's backup image try that one download it here.
Also Aliens are fussy do not have a deep file structure by that I mean keep the image files in folder on the root of the usb not in one folder in another folder etc.. although you may be able to navigate to the image files using the E2 upgrade plugin and it will even say success the image will not get flashed.