I do not own a Mz5 (yet) and hove not done this on a Mz5.
That said, changing transmission fluid is not much different than an oil change (without the filter even) but the process is slightly different in a manual vs auto. Unless the Mz5 is somehow magically different the process should be pretty standard in all cars. I would recommend this be done at the 60K to prolong the life of the transmission -it is a vital component. Steps below are summarized so you get an idea.
Manuals have both a drain and fill plug. On a level surface, remove both the drain plug and fill plug to let out the fluid. Close the drain plug and use a siphon pump to fill it back via the fill plug (or you can take apart the transmission consol to get access downwards or flip your car upside down). Fill back what you took out and check the transmission dip stick done.
Autos dont have a fill plug, only a drain plug. You would need a funnel with a long tube to fill it back via the transmission dip stick tube. Drain via drain plug, close plug, and fill via dip stick tube. Check to make sure you put in what came out done.
It is recommend to cycle through the gears when draining and filling up. You can also drop the transmission drain pan to really clean the fine metallic gunk but it is not necessary unless you are really high mileage or tough on your transmission (a little more tedious but also simple process). I HIGHLY recommend using higher grade gear oil, if you plan on keeping the car a while. It cost a few bucks more but prob wont have to deal with another transmission flush for a while dare I say the remaining life of your car. I recommend one of the following: Royal Purple, Amsoil, Red Line.
Side note: Considering the Canadian winters, your coolant is prob the most important if you have not done so. The constant cycling of hot (driving) and cold (nights/winters) will break down oils and solvents faster. Everything needs to be flushed or at least drained/refilled at some point b/c no oil/fluid last forever. Not changing them is what causes seals to break down, gunk to build up, and rust to occur (coolant systems, block). It sucks to pay for this b/c you dont see tangible results as the benefits are long term and intangible.