Here is a tutorial from NGDCC, using (naturally) a NGDCC decoder.
http://www.moemoe.gr.jp/~chacha/dcc/de22x6k/The NGDCC DE11x6K decoder has roughly the same dimensions as the Digitrakx DN163K0, but the Digitrax decoder uses some pretty large components, and has large LEDs wired in that would interfere with reassembly. You might have a look at using a TCS K0D8-D and a pair of right-angle surface mount LEDs. If you don't mind soldering all that together, this looks like an easy install.
I thought it would be like the KIHA110, too, but it looks like the internals are radically different...