The "sphag n bag" method may be your best bet. You can read about it a bit more here on this thread: http://www.rv-orchidworks.com/orchid...sgiving-2.html
IME, however, dens are often reluctant to form new basal roots. If this is the case for yours, it may instead respond by forming keikis along the cane. If that happens, still follow the "sphag n bag" treatment but once a keiki has formed roots a couple of inches long, it can be separated from the mother plant and potted up.