Parked here yesterday and scoped out the lot. Didn't see the harbor entrance, but the left side of the Clementine entrance has a sidewalk and doesn't say no pedestrians like the bus lane does.
We walked back from the park through that entrance.
A word of caution - we had a 30 minute wait for the bus at 8:10am
I checked out Google earth and there is also a sidewalk to enter from Harbor. We're staying at the Homewood Suites so, yay!