Jcopilot - here's a link to a short writeup about how I did this on the Allegheny. It includes some photos and parts list. BTW, this was on the production run before the factory installed DCC came out. Really was very straightforward, and with the big tender there's lots of room to work.
http://www.bearweb.com/hawksnest/dccfor2666.pdf
Hope this helps
Charles