Yes, it is possible to add more than 1 civ, but it needs some time to combine them. You would have one exemplar of a file for each civ and you would have to copy'n'paste all
new entries into one single exemplar of that file plus the default entries coming with Civ4 Warlords. It shouldn't be too hard (the new entries will be marked with a characteristic string to make them unique, so they will be easy to recognize), but it will take some time.
I really don't know if there is a warlords civpack. Maybe Civ Gold? Since BtS is out, Warlords mods became rare. At the moment I am working on a Warlords version of my mod, the Magyar mod (which is about Hungary,
see this thread). At the moment beta tests are running. But it will take some time till it will be published. That depends on when I get some new graphics. The links you can find in the mentioned thread are all about BtS (I should and will rename it soon). BTW: you'll should update your Warlords (the last version was 2.13 or even higher) before you download my civ one day (if you are actually interested in my mod).
At the end let me say that this is the wrong place for questions, this is for finished civs only. For questions there is an own part on this forum. I know that the place for questions is unsorted and lots of modders usually don't check it, but you make life hard for the admin if you post in the wrong place. Be sure that this will be moved soon.