I really want to do this to my MBP. I ordered both the filter and a sticker. I have not found a guide yet on how to disassemble the MBP 13" 2009. =(
It's much more difficult to disassemble the unibody MBPs display housing.
http://www.missionrepair.com/Articles.asp?ID=178
From the link above, it seems that is what's required to get at the Apple logo to change the insert. Much easier to do it with a sticker...