I see from the US ordering guide posted
http://x3.xbimmers.com/forums/showthread.php?t=445900
that they are a stand alone option (code 465) for $200, or included if you get the Cold Weather Package (ZCW).
I wonder what's the deal in Canada and how dirtdevil managed to get it done. We don't have a Cold Weather Package because heated front seats and steering wheel are standard here, but unfortunately, heated rear seats or the 40/20/40 seats are not only not standard, it seems cannot be ordered.