There's a thread with Metasequoia goodies here, but here's the direct link to Keynote. The zip has a couple other plugins included. Keynote is the one named "bone". You'll also need the included "ExportDotX" plugin wich lets you save the animated x models made by Keynote, but the other plugin(s) in the zip are unrelated optionals. There's also a document here with a basic description of the controls in Keynote. There is a seriously outdated animated MDL tutorial Here.
The main thing that is no longer correct in the tutorial is the information about "anchors". They are what bond a mesh to an animated "bone" in keynote. We found a much easier way to do it:
- Cover each bone triangle in a unique material. Doesn't matter what color or properties the material has, it just can't be used on anything except a single bone-triangle
- Add "-[unique material name]" to the end of the object name for any mesh you want to move with the bone.
For example, if you want a mesh named "crystal" to move with a bone that is covered in "material1", then change the mesh's object name to "crystal-material1". So you don't have to make any of the "anchor boxes" mentioned in the tutorial doc.
FYI, about pedestals, they have a copy of their "key" hidden inside the base. When the player uses the key item near the base, SoM removes the key item from the player's inventory. Then the pedestal, which is an animated MDL model, insta-pops its hidden copy of the key into the air above the pedestal, and slowly floats it down into place. Making it look like the player inserted the key.
If the player "examines" the base again, SoM adds 1 key Item to the player's inventory and the pedestals floats the key out of its slot, then insta-pops it back into hiding- making it look as if the player picked it up.
Attached is an animated Skull Pedestal MQO I made for someone here awhile back. If you have any troubles, just say and we'll get you set up. 
The main thing that is no longer correct in the tutorial is the information about "anchors". They are what bond a mesh to an animated "bone" in keynote. We found a much easier way to do it:
- Cover each bone triangle in a unique material. Doesn't matter what color or properties the material has, it just can't be used on anything except a single bone-triangle
- Add "-[unique material name]" to the end of the object name for any mesh you want to move with the bone.
For example, if you want a mesh named "crystal" to move with a bone that is covered in "material1", then change the mesh's object name to "crystal-material1". So you don't have to make any of the "anchor boxes" mentioned in the tutorial doc.
FYI, about pedestals, they have a copy of their "key" hidden inside the base. When the player uses the key item near the base, SoM removes the key item from the player's inventory. Then the pedestal, which is an animated MDL model, insta-pops its hidden copy of the key into the air above the pedestal, and slowly floats it down into place. Making it look like the player inserted the key.
If the player "examines" the base again, SoM adds 1 key Item to the player's inventory and the pedestals floats the key out of its slot, then insta-pops it back into hiding- making it look as if the player picked it up.
Attached is an animated Skull Pedestal MQO I made for someone here awhile back. If you have any troubles, just say and we'll get you set up.