They way I do it,
Res the Vista AO in world.
Right click and edit it.
Go to contents tab.
Create a folder in inventory to hold all the animations you are going to copy.
Drag and drop all the animations from the content folder to your new folder in inventory.
Close the edit window and pick up (or delete) the AO from in world.
Of course once you have a copy of all the animations in your folder, you can go through keep just the ones you want. Delete the silly walks, stands that move too much or turn away from where you want to face or whatever. You can always get them out of their AO again later if you need them.
Now, to add new animations to the AKEYO AO
Res the AKEYO AO on the ground.
Drag an animation from inventory to the HUD on the ground.
Wait for the animation to be recognized.
Drag and drop the next animation ...
Once all animation are add, pick up the AO from in world and add it to your HUD.
With the newest Vista AO's this will not work. They have basic animations for legs and torso and then extra fidget animations that only move the arms. When playing, different stands and different fidgets can be played in a mix and match fashion. Which is cool and gives more variety. However, when we poach the animations for use in a different AO, they are all separate animations. Your new AO won't know what to do with them.