I am local (almost), let me know if I can help. All my other high end cars have been forced induction before this one and I miss the surge. I am working on my other German car, now pulling 23 psi on a stockish 5 cyl motor!h:no its not a tease i am a technician for 20 years my specialty is forced induction and nitrous been doing that for years in jap cars did two bmw m3 turbo e36,but my loved is always bmw now that finally purchase my second m5 first one is a 1991 sterling silver and a 2000 le mans blue with blue and black interior i am new to the m5board will be posting pictures soon.i just open a little performance shop 7th av between sunrise blvd and broward blvd fort lauderdale florida area i started workind on the turbo set up wont be xpensive like most shop once i got my car perfect with no problem then i can start other project. i dont want to say how i am going to do it yet cause i am the underdog dont want somebody with more money than me steel my ideas cause it happens before anyway i will be postind pictures as the work progress before i forget i am also doing my friend 2007 m5 v10 twin turbo that will be done after mine.i will keep in touch remember IF YOU NOT BLOWING YOU NOT GOING.later
I am no expert, but the computer side of the equation has been done for forced induction (supercharging) on the S62 motor. While turbocharging has some different characteristics (immediate SC spool up vs. turbo lag for example), I wouldn't think the differences are so big that the computer program for SC wouldn't be a good base line. My point is that getting into the computer for forced induction has been done.I didn't say you didn't know what you are doing. I am simplying saying that amoung the cars out there, this will be one of the toughest to do so.
My comment may sound cautious/skeptical because I've researched in depth trying to get into the MSS52 ECM and anyone who knows anything isn't willing to reveal anything. Furthermore there are only two programs available that can open the programming of the ECM and both are near $15k (WinOLS is one but you need the full version to get anything of use).
I'm not doubting you have the knowledge or the ability to take on and complete such a project. I'm just trying to give you a heads up that it's going to be a "beast" of a project, pun intended.