The walk takes about 20 mins...the boat takes 25 mins, Epcot to DHS. If you are walking from the S/D, it will be about 15 mins. The boat from the S/D takes about 15 mins, and you have to figure on possible wait times. You can take a bus from the front of Epcot to DHS, but you then have to walk all the way through Epcot, and wait for a bus.
Walking is very pleasant. IF you are walking directly from Epcot, head out the International Gateway, go up the hill. When you get to the top of the hill, go left, over the bridge. You are now at BW. When you get to the boat dock/Village Green area, head left, past the Village Green. You want to go by Wyland Galleries, will be on your right, with the green on your left. When you get to the little tunnel area, go right through the tunnel. You will come out at the pool area, stay to the left, and pass through the pool area. You will come out on the sidewalk to DHS. Go left and keep on truckin'. It should take you abut 13 mins at this point. The sidewalk runs alongside the canal...very nice walk.
Or, you can just walk all the way down the boadwalk and take a left at Jellyrolls and a left at the start of the sidewalk.