Nope, not at all. The relevant file in this case is CRUSADER_BUILD_PROD13.TXT, and it's in the main MTW directory. You can open it up with any text editor, or something like Excel will make it a little more organized. Still, for something this simple, Notepad would be fine. What you do is search for CHAPTER_HOUSE (without the quotations). It'll jump to the line for chapter houses (duh ;)). There'll be a block of text, and at the end are a bunch of factions (starts with FN_ENGLISH, ends with FN_SICILIAN). To give the Danes and Poles the ability to build it, simply add FN_DANISH and FN_POLISH to the list. Use the same format that it currently has (when you add them, make sure you add the , as well). That should be it. :)

Bh