The boat leaves from the marina - which is right by Pioneer Hall and the Settlement Trading Post. It arrives at MK in the same area where the monorails and buses let people off, right by the main entrance. You don't need to take monorail. It's about a 20-minute boat ride!
I've always liked the boat ride to the MK... nice way to relax after a long day at the park... and, even better, if its a nice day sitting with DW in the outside seating area...
Even better... went one year in Feb when they used to have a launch that ran from the Marina to the Poly. The parents dragged the whole family on the boat for Sun mass to the Poly in a cold driving rain... now there was a fun trip