Yeah, Koshling's right; I'd been wondering about the svn version for a while, and eventually I figured that I'd wait for a major release before updating the .cpp file that contains my "mod mod" information. Since it is indeed impossible to make it modular due to its modification of the dll, it can only be stand-alone. I'll see if I can't upload the dll onto mediafire or something for players using C2C V24, and maybe I'll upgrade it if/once V25 is released.
It's been a very interesting addition so far. Being that I tend to play as culturally massive empires, culture usually makes it easy for me to dominate and push borders around, and with the hard fixed borders mod, it makes it impossible for me to bully around culturally weak nations. However, the culture is still there; a plot retains all of its cultural information, but simply maintains the ownership of the original owner. Thus, while the cultural information states who should own the tile, past politics determines who actually owns the tile.
Although, on my current gigantic 5 preset earth game, it's progressing incredibly slowly as expected due to the Eternity Prehistoric settings and the 24 other civilisations I spawned meticulously by creating barbarian civilisations on a tiny island in the middle of the ocean. Luckily for me, as China, I have most of my neighbours in the game; Tibet, Mongolia, Japan, Khmer, Siam, and India are all in the game at the moment, with an honourable mention of Tupi serving as the Indian civil war participant (South America had spawned a Brazil so I opted to use them). Culture is washing back and forth in the Yunnan area, with constant wars between India, me, and Siam knocking the borders around. I lost around three cities there on different occasions due to the Indian tendency to make utterly enormous stacks of wardogs and javelineers, which unfortunately overpower my 4-5 archer garrisons. Eventually, our relations stabilised and unstable borders appeared, which culture constantly shifted. I was irritated by an Indian city in the location where Kunming would be (on the mango resource there) so I razed it in a later war and established my own city, which I aptly named Kunming.
Unfortunately for me, they kept building forts around it, and since we had all gained fixed borders at some point in the interim, Kunming was starved of culture and it could not push India back. Just like in real life, I had to wage a war to seize some of the land that I had large amounts of culture in, and after doing so, I offered them some gold in exchange for peace, and we're at a shaky peace once more. I don't think the AI knows how to claim or anything, but I'll look into that. Either way, it's made the game much, much more enjoyable for me.
One very nice benefit to the dll edit is that I can now paint the terrain using the worldbuilder territory tool, meaning that massive empires with large desolate areas is now possible. Normally, places like Kazakhstan (which is just an enormous, useless salt flat) and Siberia (endless coniferous forest atop useless marsh) are simply ignored, but now I can paint them over with the nation/civ of my choice. At the moment, since Russia is still basically just Muscovy and shows no intentions of changing any time soon, the Mongols occupy much of Siberia and also much of Kazakhstan, the Gobi, Turkestan (there's no Chagatai Khanate so they'll have to do), and Manchuria (no Jurchens). Egypt claims basically all of North Africa save for what Carthage claims, and I used Russia to block the Sumerians from settling in Finland (which they kept doing).
Again, I realise that my style of play differs from those of many; those who play to win would find my fixed borders mod mod to be irritating since it prevents border flips due to culture, and other civilisations that like to spam forts would make it impossible to settle cities without going to war. However, I have a more roleplay-oriented style, e.g. try to fit history, so I'm very pleased with the result.
Thank you, Koshling, Thunderbrd, and the others for making it possible for me to make C2C perfect (for me)!