As a stopgap, please consider using the MAF Translator to perform tuning on the M112.

It is pretty cheap and converts the stock MAF sensor into a MAP sensor with full injector control based on boost.

http://www.maftpro.com/tproinfo.shtml

To control spark timing with boost retard, use the MSD Multi-Channel Boost Retard controller or equivalent.

http://www.msdignition.com/sci_3.htm