OK There are ZERO tutorials for this so i thought I would put one together.
Basically follow the steps for the microfilter replacement which can be found here:
http://www.318ti.org/forum/showthread.php?t=7836 The next step is to remove the battery and battery box. There are 2 13mm bolts that are clearly visible at the bottom of the box, remove those.
Next you need to remove the foam insulation that is on the firewall, there are 3 push rivets there that should be easily removable with a screwdriver. Once you have that foam insulation off, there are 4 phillips screws that hold on the wire channel. remove the 4 screws, they are captive so don't take them out fully. Once they are out you can move the wire channel out of the way to give you some more room to remove the blower housing and blower.
Battery box, foam insulator, and wire channel moved out of way:
3 Views of blower cover housing: