There are essentially four components. The first is Regalia Flags proper. In that package will be a .pack and .esf file. The .pack Goes in your data folder while the .esf goes in your data / Campaigns / main folder. If Darthmod does not use a .esf (and I don't think it did last I checked), then this should be fully compatible.
The second component is the sound mod, which simply goes in the data folder.
The third component is the smoke and blood mod, which actually has several variants. Nonetheless, when you download the full .rar for the smoke and blood mod, there will be four .pack files in the .rar. I would pick one of the MM ones (either complete or the Puckle change), and that gets put in your data folder.
The fourth component is the uniform set. There is one file which has all the uniforms compiled, and is therefore the easiest. However, if you are already using uniforms, you may want to pick and choose individual sets, and Regalia has links to individual uniform downloads. I personally suggest at least the Ottoman and Russian full re-textures, but they're all very good. These are also .pack files which go in your data folder. Unlike the previous three, most of the uniforms are in patch format.
After you've done that, use the Mod Manager (I assume you're using it) to activate all of them. Only the uniforms won't require it, as they are automatically read when you load the game. I hope this has been helpful.
Main Regalia Downloads (there is also a link to the Mod Manager there if you don't have it)
http://www.twcenter.net/forums/showthread.php?t=259304
Post Script- I don't know about Imperium Globale. But in general, Regalia will work with most mods. The only ones it won't work with perfectly are those that have their own .esf, and those that modify the Factions database. Mind you, it still works, you might just end up with some funny business. In my own game, my Spaniards are wearing yellow coats but have the correct white pants. I'll admit it looks snazzy, so I haven't bothered trying to fix it.