That's probably too tall an order. I think the California mod is pretty much an overhaul of NV rather than a new land/DLC thing right? That means that the NV stuff would be gone so you'd have nowhere to go on that trip. The game would be trying to load NV, but the NC mod would have overwritten a lot of it so it'd be real wonky. The reason TTW works is that 3's game is entirely separate and does not override anything. The base game is NV, not 3. 3 is just tacked on and needs a largely intact NV.
That's just my understanding. If NC is a standalone, then it could potentially work, but if it's the mod I'm thinking about, it's a total overhaul.
For more information, you may want to post on the TTW forums.