How can I add steam library artwork for the project?

[slipperfish]

Steam finds this icon with \Halo\VR\OpenVR\haloce.vrmanifest

The steam library also tries to use it for the poster art, but it's a bad fit for that aspect ratio. I was wondering if steam could read a manifest for header, icon, library_600x900, libary_hero, logo, etc so HaloCEVR has complete presentation art in the steam library, even if it's a non steam game.

The most I was able to figure out is \Steam\appcache\appinfo.vdf is where that information is normally stored. But I can't read the whole vdf in plain text. Just wondering if anyone knew what to do, thanks.