Open the root directory of the mod and find the ..\Among Us\TOHE-DATA\Tags folder to get started!
This folder holds 4 files (by default), 3 Folders (MOD_TAGS + VIP_TAGS, + SPONSOR_TAGS), & a Tag_Template.txt file.
You can disregard the 3 folders as those use a separate system of Tags, the new system utilizes the Tag_Template.txt file.
When you open the Tag Template, you'll see some lines to fill out, first Copy the Tag Template so things are easier (The mod will automatically generate a new one if you've lost it), then you can fill this out however you want to give a user a Custom Tag.
You can leave most of it blank for a default tag (display) or edit the other lines with info for specific permissions. The file explains it clear enough, so use that.
Once you've filled out the file, you can rename it to the friendcode of the player you want to have the Tag (Like friendcode#1234) and you're set.
If you'd like to sort your friend codes into custom folders, you may, and it will automatically be checked AS LONG AS it's in the Tags directory. (Note: Don't name the folders any of the following: MOD_TAGS, VIP_TAGS, & SPONSOR_TAGS, as those use the old Tag System.)