I have been trying to follow the alternative code readers for the SPi Minis.
I finally put together this page that collects what I have found:
http://www.tmsmini.com/cooper/mini_efi3.htm (http://www.tmsmini.com/cooper/mini_efi3.htm)
I think I have the links updated as many of the sites are not maintained regularly as things change.
Updates are frequently found in the Mini Forum UK:
http://www.theminiforum.co.uk/forums/topic/34741-spi-code-reader/page-11 (http://www.theminiforum.co.uk/forums/topic/34741-spi-code-reader/page-11)
I also attached two documents, one is an overview from Car Mechanics(May 2016) and the other an overview of MEMS Rosco.
If you find some links that are not correct let me know. I realize there is a limited audience for this information.