try
www.Bimmerdiy.com
your best bet is to google it and see if you capable of such a mod- if you don't feel comfortable with it, phone around and get quotes, maybe it wont be that expensive.
the problem with DIY is that you do need some knowledge of what is important, and it is a time consuming exercise, you don't want to get half way and realize its beyond you.
hope that helps a little?
some guys will disagree with me, but its just my opinion.:thumb: