I spent at least an hour looking for it with these maps:
https://www.msu.edu/~oconne53/eqatlas/freeport.html
http://wiki.project1999.com/Freeport
The door to the building in East Freeport is locked and I can't find the entrance to the tunnels either in the Inn or anywhere else. I couldn't find a map with coordinates so /loc didn't really do anything for me, and not having Sense Heading is only slowing me down further.
I also tried to find video guides on Youtube but no luck.