From what I've read here and there, modders are still unsure about how the Havok depository functions and are trying to figure it out. It's probably not the same system as used in Skyrim. If the GECK supports that particular system, things will be easier for modders to make animations. If not, it will take some time to figure it all out and make something useful. I have little to no knowledge about this, so I might not be 100% accurate.