I would say that the answer is "yes you CAN use a controller, but you won't like it".
Any 100% DirectX compatible controller that can have it's buttons mapped to keys can be used (MxO doesn't acually support controllers so there aren't any in-game settings for them)
HOWEVER
Most controlers only have 8-12 buttons and MxO requires 2-3 mouse buttons and most of the keyboard. I'd have to compare it to using a controller to run Word... you COULD do it, but it wouldn't easy or fun.
Save yourself the heartache and don't try.
P.S. for a testing point of view, I actually got character movement to work with my Microsoft force feedback steering wheel, but I ran out of buttons to map. It can be done but so can many other stupid things
