I am following these wiki instructions but it's still not working...

[captmorgan72]

FFVTTR: Pasting pieces onto another mesh in FFVTTR is similar but slightly different. Firstly make sure all the meshes you are going to be working with are converted. Then open both meshes up in Nifskope. Find the piece on your source mesh which you want to copy and right click "block/copy branch".
Move to your mesh that you're adding to. Find a piece on that mesh that is in a similar place to the one you want to paste on, note down it's node number. Then go to the main node (top one), right click "block/paste branch". Then remove the branch of the piece that was on the mesh originally. Use Ctrl-up and Ctrl-down to move your newly pasted piece to the node that the previous piece was on, then you're done.

I can get the mesh piece in place but in character tool and in game the piece floats about and stays detached.

[Cyber Burn]

   Usually, when I skope, I paste the copied piece onto the (0 NiNode). Whatever I pasted usually goes right to where I want it, with some exceptions. But as far as floating pieces, I think it has something to do with the "NiSkinInstance", I think I read that somewhere. Unfortunately, I usually end up deleting things and starting over when this happens, it's a bit above me. Hopefully someone a little more skilled can help you out.

[Boalt92]

I've found that, more often than not, the translation of the piece ultimately determines where it goes.

It is expressed as x,y,z coordinates, and is relative to the parent node to which you are pasting.

For example, if the piece you copied is x=500, y=250, z=0, and the node you are copying to is at x=700, y=300, z=10, then the actual position of piece is x=1200 (500+700), y=550 (250 + 300), z=10 (0+10).

Cyber is correct, the best way around this is to try to post onto the 0 NiNode, whose translation is x=0, y=0, z=0.  If you're dealing with similar models, you might be able to get away with pasting it onto it's respective node on the new piece, but you might still have to tweak it a little.

DISCLAIMER: I have found this to be true for all the maps I've skoped.  While I've skoped a few character meshes, I can't say for sure that this will apply for all of them.