Here is a Skyrim Creation Kit tutorial video showing you how to create a custom chair (out of almost anything) for the player to use in Skyrim. It also shows how you can create new object types using existing nif files, without having to export/edit them.
Below is the script needed to make it work (as used in the video). Hopefully you find this helpful.
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ObjectReference Property ChairMarkerREF Auto
Actor Property PlayerRef Auto
Event OnActivate(ObjectReference akActionRef)
if akActionRef == PlayerREF
ChairMarkerREF.Activate(PlayerREF)
endif
EndEvent
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