http://www.atlantareefclub.org/forums/showthread.php?t=14389&highlight=reactor+chamber">http://www.atlantareefclub.org/forums/showthread.php?t=14389&highlight=reactor+chamber</a>
That is my thread describing how I did it. The pics are gone, but the verbal part is there. It works well.
If you want ome of those external canisters, I think many of people on here have them. You might just post a WTB and find one on the cheap.