This will give you a good start. I think Jake is now in Eastern PA, but he could probably be located if you had any questions.
http://www.bikely.com/maps/bike-path/Pittsburgh-To-Antiochian-Village
Here's another route that I've considered using, but HAVE NOT field verified..... It would take you from West Jeannette to the GAP at Boston. Trail could then be used to take you into South Side, with caution used in vicinity of Sandcastle/Glenwood Bridge.
http://www.bikely.com/maps/bike-path/Jeannette-PA-to-GAP