I just did this service on my 08 M3. My car only has 42k on it and I paid the dealer to do it once before. At any rate, the reason for my post is I used my brand new Motive fluid pump when I did it. It's basically a glorified garden pressure sprayer. If you are crafty you could make your own for less. But I have rigged up so many pumps over the last 20 years and tried all kinds of cheap POS pumps, I wanted to try a nice one for once. This is it. It is a pleasure to use. I pressurized it with my compressor and it filled the transmission fluid in about 1 minute on a single charge. Love the tool. I will use it on the M coupes next and on our GMC truck too.
http://www.ecstuning.com/Search/Motive/ES2207920/