The process is the same as editing any mod map. You don't need to take any files from the Default Types mod, you copy them from the game install folder and place them inside of your map mod zip.
The two main files are maps_fruitTypes.xml and maps_fillTypes.xml. These can be found in your game install data/maps/ folder. From there you reference these files the same as you would with any other mod map inside of the map xml file for your map mod. The only difference is the addition of the "thDefaultTypes="true" part.
That activates the process. From there you just edit your values in the map embedded xml files you copied over.
You really only need it for maps that either do things that the vanilla game does not allow, or to fix double registration issues currently on some maps. The second issue, however, I imagine will be fixed next week because it is a game bug.
Hope that helps!