I am using rigify on my blender character, but I added some extra bones because my character has wings. I'm trying to make the extra bone I added become one with the rigify add-on. How do I go about doing that?
You can add new bones without modifying the script.
Just create new bones or duplicate existing bones in the MetaRig, before generating the rig, orient and parent to the bone you want them to follow, then, in Pose mode, set the rig_type in the bone options.
The rig type determines how rigify handles the new bones. Wether it will create controls, etc.
The rigify addon generates all the rigging through python scripting. To extend the rig created with it you need to add and/or alter some python scripts.
The README included with the addon provides a description of how it works and how to extend it. In simple terms you define a class with
generate methods that generates the control bones and widgets for your wings. The main key to making it work is the bone names used, the script that generates the controls is chosen based on the bone names.
For a one off rig I would suggest manually creating the controls for your wings. You can use rigify to create the main body rig, then add the controls for the wings, they don't have to be generated to work with it. If you are looking to have the addon generate ik/fk controls for you then you could try naming your wing bones as shoulder, upper_arm, forearm and try the rigify generate.
If you would like to make your wings a permanent part of the rigify addon then read through the docs and scripts in the addon to see how you can add to it. You can submit your additions to developer.blender.org to be reviewed and considered for addition to the addon.