The current plan according to the above jira issue is to provide a number of DeploymentUnitProcessors in org.jboss.as.deployment.processor that would parse modules specific manifest headers and provide module wiring configuration through this mechanism. Have a look at ModuleDependencyProcessor for an initial implementation of this.
* How these headers related to existing standard OSGi headers
A good starting point would be a documented set of supported headers and their associated sematics - this can be done in javadoc (preferred) or wiki. Starting from this we can then expand on the ideas and provide feedback