Well, you definitely have to remove both the blower motor and the case it is in.
The heater box I am talking about is the part under that, the huge box that sits on the transmission tunnel under the dash that contains all the heating/cooling stuff in the car - heater core, evaporator, the controls, ducting, etc. You'd have to remove the dash, drain the coolant, and evacuate the AC system to get it out.
I doubt that removing that would gain you much more than an inch or so of room, but I think it would be enough to pull the wiper linkage and motor together. I can't see how the heck they would fit out otherwise.
I was half-kidding when I said that - your best bet is still to separate the motor from the linkage and pull them out separately.