There have been numerous threads about his subject on this forum in past. I would suggest you to search bit around.
In most cases people create additional module root/repository and add it to JBOSS_MODULE_PATH.
this enables you to upgrade jboss and just point it to your custom module repository where you have all your modules.
I wasn't asking about how to create a custom module and where to put it in my local installation, but for a way to package and share such modules.
At the moment, we build Maven assemblies for custom modules and publish them to our team Nexus. If anyone else is interested in this approach or has a better solution, it might be worth while pushing such modules to Maven Central.
i misunderstood your original question...
What you have looks like interesting approach and could be useful in general.
If you are up for it, can you share what exactly are you doing and how? maybe share code/build configurations so we can see what then results in maven repos.
did you go with creating custom artifact type?
What we are planning for future versions of WildFly (9 or 10) is to have some kind of repository manager that would allow users to install extra functionality like additional subsystems, shared common modules, ...
that would also allow us to distribute WildFly "core" app server that would have just bare bone functionality to boot server and no extra subsystems, from there you would be able to install what ever you would like to use on your server (java ee, osgi, torquebox, immutant, capedwarf,....)
This is big effort that is ahead of us and for now we are really open on extra input on what would be needed or even ideas how to best approach this.