- get latest Jetty 9.1 archive and extract somewhere (I'll assume the Jetty root is called "jetty")
- in jetty/lib, create a folder called "weld" and download the weld-servlet and weld-servlet-core JARs into it. For injection in listeners to work, version should be 2.2.0.Beta1 or later.
- in jetty/modules, create a weld.mod as in this gist
- in jetty/start.ini, add a single line containing "--module=weld" to initialise Weld
In most cases, that should be it and you can deploy any compliant CDI application, even without a web.xml. In some cases though you may need to add the old-fashioned filter entry to the web.xml. See also: weld/core#465