I recognize this is an edge case, but I can see value in having @EJB injection capability when using Weld Servlet in a pre-Java EE 6 container. You could go about it at least two ways:
1. provide a portable extension that satisfies the @EJB annotation on a managed bean field
2. implement Weld's EjbServices
#1 would be a great demo of a portable extension, but the shortcoming is that it's only a connector between a managed bean and an EJB. You would have to do quite a lot of work to give the EJB CDI services.
#2 would be pretty easy since you could off-load all the work of #1 back to Weld. The problem is that the Weld Listener doesn't provide any hooks (that I can see) to register services before it starts the Weld container. I was imagining something like a service-provider approach so you can shove the EjbServices implementation (+ family) into the deployment classpath. Can we add that feature?
We're really just a small step away from giving people access to CDI in pre-Java EE 6 containers. And there are a lot of people on those containers and will be for quite some time.