If you are at POP, take the bus to Magic Kingdom, then take the boat over to Fort Wilderness. From there it is a short walk to Pioneer Hall.
If you are at DTD, you have three choices.
1st Choice, take the bus to Contemporary, then walk through the Contemporary and take the boat to Fort Wilderness, from there it is a short walk to Pioneer Hall. (this boat does not allow wheelchairs)
2nd Choice, take the bus to Fort Wilderness, then switch to the YELLOW Settlement Bus, then it is a short walk to Pioneer Hall. (Purple Settlement and Orange Settlement will work, but it is a much longer bus ride.)
3rd Choice, take the bus to Wilderness Lodge, then switch to the Fort Wilderness bus, then it is a short walk to Pioneer Hall.