Photoshop :: Adding File Formats To Generator

I am interested in adding some other file formats to the newly added Generator feature in Photoshop CC, but where to start after looking at the installed scripts. I am also not the most experienced with this, so my lack of knowledge is probalby also blocking me
 
What I want to do:
 
- add TGA formats in 32 and 24 bit format based on the existence of an alpha channel
- change where the image assets are saved to be in the same directory as the psd, not one directory lower in [filename] - assets folder.
 
Have not had any luck adding TGA formats, again, unclear how to do this. Can see things happening in convert.js, however when trying to add a TGA entry to this, it fails (and deletes the assets folder)