Injection Magic allows to take a modified character and create pose files from it to add the corresponding modification to the original character. It allows to include
Morphs
Scale
Taper
Trans
Pose
MAT
settings that are different from the base character. Injection magic allows to create definition files for new characters, like ApolloMaximus 2007 or Victoria 4.
By others
Here are the tutorials we used to understand how to create our own definition and pose files: