1. Opening the asset fileNavigate to C:\Program Files (x86)\Steam\steamapps\common\Among Us\Among Us_Data, and open the file sharedassets0.assets in UABE.
When you get this dialog, just scroll to the most recent one and click okay.
1.1. Sidenote: InstallationIf you just want to install an already compiled mod for yourself, select 'Load Package File' under File instead of Open.
Make sure that all of the options are checked off, and that the base folder is set to the aforementioned data folder. Once you do that, just follow the Exporting your Mod directions below. Otherwise, keep reading to find out how to make your own.
2. Finding the texturesAfter you open the file, you'll see a screen like this. I'd recommend switching it to sort by Type so all the textures are next to each other. Then just scroll down until you see the chunk of assets that are the Texture2D type.
3. Exporting the textureOnce you find and select the texture you want to edit (They're all named pretty descriptively, for example, the sprite sheet for the game's hats is just named 'Hats), click 'Plugins', which will bring up this menu.
Select 'Export to PNG', and save the file somewhere where you can access it.
Edit your texture (in this case, hats) however you feel like. Do note that the game's sprites seem to be pretty specifically shaped around these textures (at least on hats), so try not to make things too big or differently shaped to the originals to avoid cutoff and overlap.
5. Importing your editClick the 'Plugins' button again on the same texture, but this time select 'Edit'.
That will bring up this menu. Ignore most of the settings if you don't want to change how the game uses the texture, and just press the 'Load' button at the bottom. Find and open your texture, and press OK. When the game asks for a quality setting, just leave it Basic. I don't really know what this does, but you probably shouldn't mess with it.
6. Exporting your modGo to File > Save and export your modified sharedassets0.assets. In my experience, you can't save over what you're currently editing, so you might need to save it somewhere else and then paste it in the Among Us_Data. If you did all this correctly, you should be done.
6.1. Sidenote: Sharing your modIf you want to upload your mod to Gamebanana or share it anywhere else, I recommend making an EMIP file with UABE. While you're still in the asset file you're changing, go to File > Mod Maker and select 'Create installer package file'. DO NOT SHARE THE SHAREDASSETS0.ASSETS FILE. It's easier to upload this way, but it prevents the mods from being mixed or matched, increases the file size, and hosts the majority of the game's assets on GameBanana for no good reason.
In this dialog, make sure (just like loading a mod) that the base folder is set to your Among Us data folder. You should also check in the change list to make sure your mod is actually part of the file (denoted by Replace PathId [the id of the file(s) you changed]). Then press OK, save the file, and share it wherever you feel like!