LOL. It actually was a no brainer. My problem was, in fact, I was thinking too much. If you mod jsut like the old days, you'll be OK... although now you have the resources of the vanilla civ iv installation too (for example I used the Betsey Ross style flag for the Americans which is from civ iv not warlords).
There's a "barebones" mod example that Warlords comes with in which XML files are pretty short and gives a sense of how you can edit them further. I prefer to use full length ones because I'll tinker with stats/units I didn't plan to tinker with and want them all there, so I go that way.