you have to add an animation to the model to make it spin. need to make the animation looping and make the movement speed slow enough. im not exactly sure how fast it would go. if your using 3ds max i would think the note tracks would look like this
Starting note:
Stand
MoveSpeed 30
Ending note
Stand
MoveSpeed 30
something like that, honestly i don't know if the game engine supports that low of a movement speed, i don't see why not. make sure that ending one ends on an even space... like the starting location is 0 and the ending is 40 so that it loops, if you choose something like 0 and 43 the animation wont loop.
i hope that helped you, good luck.
*edit* actually the movement speed will not work if you use it with standing, i just tried it and it makes the item spin as you move so just use the Stand note. just do the same without the movement speed and it will probably work the same. if u dont have 3ds max then upload the item you want to rotate and ill try to do it for you if i have time... ive been working 15 hr days so its hard to have anytime to do things but ill try if you post it.
*edit* here is an example i did in 3d max, open this up in magus viewer to show the animation.
