I have 6.2.5014.0 (8.1 version of MDT 2012) when I import my .wim that is Windows XP (32bit) it does create the folders and setup the structure, but its not listed in the Operating Systems folder in my MDT.
I have tried with multiple .wim images, each one fails to show up (all xp) the windows 7/8 show up with no problems.