New Tween Menu options are added by creating a JSON file in \interface\tweenoptions. Already existing options can be edited there as well.

The content of a Tween Menu option JSON file looks like this:

There is a total of 6 different properties, two of which are mutually exclusive.
skseName: The name of the menu as it is registered in the game. For the vanilla menus, the list can be found here: CreationKit Wiki - UI Script. For mod added menus using SKSE, you will have to 1) dig into the source code or 2) ask the author.
papyrus_event: The name of the Papyrus event triggering the menu. It can be found by either 1) checking the mod's Papyrus source code (if provided) or 2) asking the author.
menuName: the name of the option as it will appear in the Tween Menu.
icon: keyword for the icon to display, only used for the Alternative style. (list at the bottom of this article)
priority: the lower the number, the higher the priority. It is used to determine absolute priority for the Alternative version, and priority within each category for the Classic version.
category: category in which the option will be displayed, only used for the Classic style.
You should use either the "skseName" or the "papyrus_event" property, not both. But in case both are provided, the "skseName" property will take precedence. In some cases, we can imagine that the "papyrus_event" could be used as a fallback even though it's not its original prupose.
Icon keywords:
"inventory" (purse and ingot)
"magic" (book with daedric symbol)
"magic_alt" (flame)
"scroll"
"map"
"werewolf"
"skills" (abstract smybol with upward arrows)
"skills_alt" (hammer in a shield)
"swords"
"human"
"star"
"hourglass"
2 comments
Thanks for the mods, keep up the good work.
anyway
JPSteel2 do you know skseName of MCM Menu ?