As exist some OBJ importers for Moi, that should be not difficult to import it ! ;)
http://moi3d.com/forum/get_attachment.php?webtag=MOI&hash=1672dd45da321f51513d74216e78cd7b&filename=importObj.zip
by Max Smirnov

The free MeshLab can convert STL in OBJ
http://meshlab.sourceforge.net/

then you can use the subdivider by Max Smirnov again ;)
http://moi3d.com/forum/index.php?webtag=MOI&msg=6674.82