I don't think you can as that is a viewport area. Hopefully it is something Scott is working on for nUI 6. However, I recall the question being asked before and it may have been answered already, although a search for nUI viewport didn't come up with anything.
Ah here we go :
http://www.wowinterface.com/forums/s...t=nUI+viewport
http://www.wowinterface.com/forums/s...t=nUI+viewport
Maybe Scott can shed any more information on this area.