EDIT: I can't post it through forum's attachment system. I will save it as an .rtf (general edited text file type available across many OSs, IIRC. More OS's than .doc, at least.), so most text editors should be able to open it. To try it, open it in an editor and save it as "ulm.dm". Try putting " marks around the file name if it doesn't work without them. Remember, renaming isn't enough! If someone wants to host it, go on.
As I said, I can do it. And I did. Took about half an hour:
I chose Abysia. I cleared off its units, changed #preferredtemp to 0, took away heroes and disabled themes. After that I wrote up all unit id's of Ulmish units/commanders and added them to Abysia's recruit list. (In the first Version, Second Ulm got a Strategos... That was a quick fix, however. )
Then I checked Ulmish province defense with Clash of Titans, Caelum vs Ulm. I saw a battle that took place between Ulmish provincial defense and lone Caelumian scout, wrote down the unit id's and approximated the number of units. 10 units/10 points of pd in the case of Ulm. Forgotting this would give Machaka-Ulm extreme province defense!
After that I replaced starting units, cleared off starting sites and added The Forge of Ulm and The Keep of Ulm. Both nations were able to recruit Guardians, both nations had both sites. It seems starting unit types can't be modded to contain two types of units, so I took off 2 of the 14 starting Infatry and made all shielded ones. I tested this quickly, found out the bugs about Strategos and starting units, fixed them and sent this message, so if it doesn't work try bothering me tomorrow. I didn't check provincial defence.
Few things I found out: starting units must all be of the same type. "Unique" sites can be doubled. "Nation-spesific" units can be recruited from multiple doupled sites. I didn't check if the nations can recruit special units from each others' capitals. It is not worth changing the flags. This is quick and simple: the (modding) manual is all one needs. Ulm-spesific fortress boni can't be doubled ATM. National heroes can't be doubled, but they can be disallowed: no heroes for the break-outs, they are loyal to the main nation.
Quesses:
National pre-researched spells can't be disallowed if the game doesn't quess the right one (both the nation-spesific and the normal one have the same name). Nation-spesific spells can be added, but this takes the spell away from either all other nations or the original nation. I haven't checked how that works.
Boring:
Descriptions, nation pop-up texts and short military/priest/magic power texts might have to be copied by hand: they can't be just copy-pasted. If someone can make black&white picture of the text screen and put it full-screen he should try print screen - paste at notepad. It did work for roguelike screenshots!