If anyone is interested in this retro-fit I've managed to colate all the information in two Word documents (1st is the physical installation and the 2nd is the coding stages). They are mainly other peoples work but just all together with some additional information especially for the e89.
They are on my DropBox account ....
Part 1 >>
https://www.dropbox.com/s/3qj1ty50rg...t%201.pdf?dl=0
Part 2 >>
https://www.dropbox.com/s/ltfnhvygop...t%202.pdf?dl=0
(Part 2 now includes links to new profiles and SPDaten files as well as instructions on how to load them)
I hope that is of help to someone.