If you install the 3.0b viewer to a different folder, you still have the old viewer. However there is the phonebook issue, since the two use the same paths. a workaround is to create a blank phb in another location instead of making a blank one over your old one. rename it and place in the default path under application data. use the old 3.0 viewer as before, but never create a new phb when 3.0b starts. then pick "set phonebook" from the menu and use the one you created b4. You have to close the old viewer to use the new and visa-versa.
BTW the new viewer works for telnet, file transfer, and others with 2.2 servers, just no video.
and you can run both 2.2 & 3.0 servers on one machine as long as you use different ports.