BMW: Cabin Microfilter, bmw 3 series, model bmw

Question
I can't seem to find any instructions on how to change this filter (cabin microfilter) even though it seems to be a regular maintenance item. I have a 2002 325ci Convertible and prefer to do the basic maintenance myself. Can you help with instructions ? Or make a referral pls. Thanks  

Answer
Roby,
 my area of expertise is the older model BMW 3-series (e30) 1984-1991.  I have replaced a cabin filter on an e36 1998 M3, but as far as your e46 I have not done one of the late models.  The filter on the e36 was under the dash, in front of the passenger footwell and a little toward the center of the car.  It was a pain to get to, but it wasn't out of the scope of a basic mechanic, with basic tools.  

 I would search the forums for instructions.  I found this, although I didn't read it completely, it should be similar to your car.
 http://www.bmpdesign.com/technical/install_instructions/e46_cabin_filter_install...

 Hope this helps,
 Josh Fields