How to add custom HTML and JavaScript to my Windchill Action button

Hello Everyone,

I am trying to add custom html and js scripts to my Windchill UI components. To be specific I have a custom action button in more parts action drop-down menu (image attached). I want to customize its html and add some JS scripts which are to be triggered on click. 

From my knowledge PTC's official customization guide does not cover such UI customizations, but I have seen others on this forum make some implementations. Any guidance regarding this will be appreciated.