Installing the viewer with 2.1M5 onto resin:
1) follow the instructions on page:
http://www.eclipse.org/birt/phoenix/deploy/viewerSetup.php
2) inclucing the 2 extra files here:
http://www.eclipse.org/birt/phoenix/build/#j2ee
3) Do the undocumented step of downloading commons-logging.jar from
http://jakarta.apache.org/site/downloads/downloads_commons-logging.cgi
4) unzip it, get the commongs-logging.jar and put it in the lib of the viwere webapp. Now you can run the example reports.