This was tried in Harrisburg about 10 years ago. WCMB AM 1460 had an all "hot-talk" line-up: Imus, Liddy, Don & Mike, Tom Leykis. Imus and D&M were simulcast on their FM station (99.3?). The FM simulcast didn't last long.
IMO, this doesn't have anything to do with Central PA not willing to accept non-conservative talk. "Hot-talk" isn't the same as liberal talk. I think Central PA isn't crazy about "boobies and boogers" humor for hours at a time, and that's what "hot-talk" generally boils down to. (I make this comment as a long-time fan of Don & Mike.) I think it has to do with Central PA FM listeners not wanting to listen to talk. They want music.
GOOD liberal talk-shows will pull an audience in this area. Mark Wainright had a great local, left-of-center show on WHP for a number of years. I was told by a WHP exec that they would kill to have him back, but he wanted out of the business. I would listen to Alan Colmes, as I did when he was carried a number of years ago by WNZT. He's a good broadcaster and a very liberal guy. Air America simply isn't good radio. It's shrill and lightweight. Ed Shultz is horrible.