Modding national undead

[Nounours]

Well, I'm back to modding (at last !), and I have a problem with undead...

No, not the classical rampaging zombie sort of problems, just a modding problem : how can I mod my national undead to be summoned by classical spells like Reanimation ?

In other terms, Jotunheim, for instance, reanimate Giant soulless or skeletons. I would like to do the same with my mod, but with my own national undead. And by the way, how do I mod my undead units to make them national undead ?

Thanks for your help !!