Unless you understand German and have solid contacts in their Mercedes tuning community, you're going to save a hell of a lot of time and money by getting in touch with the experts here in America.
It's not very hard to dump an image or reflash the ECU (there are a few common tuning software packages that can do it), but once you've got the ECU image there are very few people who know how it works.

Eurocharged Performance are the experts in this field and you should probably get in touch with them - all of my dealings with them have been fantastic, and I suspect they probably know more about the inner workings of Mercedes ECU code than anyone else in North America.

The guys at Accelerated Industries also have some ECU experience, but I believe it's more oriented towards using DAS/Xentry (the OEM/official Mercedes diagnostics software) to reinitialize ECU security and allow other Mercedes ECUs to work with our cars (for V8 swaps, SRT swaps into N/As, and so on). They're also great people, though, and probably have some pointers.