Haha well...........
Start with this:
http://bmw.e30tuner.com/articles_mafcon.phpI am now a lot further along with it, but it is still not quite ready to sell. The Mustang MAF guys use the Spluit Second kit, which I hear requires a LOT of re-tuning constantly, and it is like $1000.
Unfortunately, the conversion is not something most people can DIY (unless they have chip burners, a wide-band O2 sensor, logging software and a compatible logger, good soldering skills, good fabrication skills and an extra air box).