OpenWrt support for Zyxel LTE5398-M904

I don't wish to sound lazy but there is a great deal of information in this thread which is quite fragmented and difficult to follow.

I just purchased this Router and wondered if there is a more consolidated guide on the process of flashing it with OpenWRT - can I simply download the firmware snapshot and flash it directly via the web ui or do I need to go through the entire process of obtaining root, setting up the build environment, building the rom from source etc?

Sorry if this sounds lazy, I am just trying to figure out the best way of getting this setup and the thread really is quite fragmented.

Thanks in advance.