If it came down to it (preparation) I could do it in a weekend, however, I'd like to hold on to the car to test everything to warranty the work.

I want to assume he is that far. There are a few problems he's going to have... First he has to find what PROM to extract, then it's a matter of extracting the maps from the mapping file, finding the maps in the Hexidecimal, figuring out how to alter them, and loading the new file in correctly... One company makes software capable of SOME of this and they are VERY expensive, like $30K+. To do all of it, you need to understand Checksum's, have great soldering ability on SMT's and be able to trial and error the entire process over and over. He will ruin many ECU's if he hasn't already ruined one and got stuck. If he did ruin your ECU he wont be able to fix it, just let me know and I'll fix you up for free if he give's me my damn deposit back.