Jetty 9.1.4 has JSR-356 support.
$ ls -la jetty-distribution-9.1.4.v20140401/lib/websocket/
total 540
drwxrwxr-x. 2 joakim joakim 4096 Apr 7 09:51 .
drwxrwxr-x. 12 joakim joakim 4096 Apr 7 09:51 ..
-rw-rw-r--. 1 joakim joakim 36611 Apr 2 10:14 javax.websocket-api-1.0.jar <!-- the official JSR-356 API Jar -->
-rw-rw-r--. 1 joakim joakim 156243 Apr 2 10:14 javax-websocket-client-impl-9.1.4.v20140401.jar <!-- the javax.websocket implementation by jetty -->
-rw-rw-r--. 1 joakim joakim 36802 Apr 2 10:14 javax-websocket-server-impl-9.1.4.v20140401.jar <!-- the javax.websocket.server implementation by jetty -->
-rw-rw-r--. 1 joakim joakim 43680 Apr 2 10:14 websocket-api-9.1.4.v20140401.jar
-rw-rw-r--. 1 joakim joakim 35188 Apr 2 10:14 websocket-client-9.1.4.v20140401.jar
-rw-rw-r--. 1 joakim joakim 170297 Apr 2 10:14 websocket-common-9.1.4.v20140401.jar
-rw-rw-r--. 1 joakim joakim 35774 Apr 2 10:14 websocket-server-9.1.4.v20140401.jar
-rw-rw-r--. 1 joakim joakim 17923 Apr 2 10:14 websocket-servlet-9.1.4.v20140401.jar
If it isn't working for you, can you give some details on your attempts?