What I did was alter a_testChrisRooms.xml to have my handle (so I could find it) and saved it as a new xml.
<room_setup script="SmallEW/Cinth_Zoo5"
SmallEW is the room type and Cinth_Zoo5 is the specific room of that type. Change those around to use the type and specific that you want to test.
The rest of the xml I can't say how to mess with (I just don't know).
To test your room in game, go to Mods a the file select screen. The next screen you can find your xml in the second drop down and hit OK.
Inside the test chamber you can play it over and over (win the room and it starts over automatically). You can still edit your room and when you have saved changes, you can reload the chamber from the esc menu in game.
That should cover basics of getting it to work. Have fun!