Yes, I bought the dipstick from the dealer and believe me this is not brain surgery. The dipstick is well marked for different temps.
I did learn one thing though and that is there is no drain plug in the converter. Kind of a let down because I was hoping to change all of the fluid. I'm not sure about your 98 but I know my 2000 doesn't. Confirmed from about 20, very slow, revolutions and lots of bright light, NO DRAIN. Oh well, I guess MB is serious about there lifetime fill to the extent of not putting a drain in the converter.