Three known ways to listen to the Sox outside of greater New England
1: XM satellite radio
2: MLB.com Gamdeay Audio (anywhere you have an Internet connection, costs about $15-20 per year, incl. Spring Training and the Postseason, as well as archives of recorded audio games for those of us who might be across the pond)
3: MLB.com At Bat app (anywhere, if you have a smartphone and can get service)
I don't see why any of these options don't apply to our Scouser friends, if they're interested. The Gameday Audio service in particular is a fantastic deal when you consider you can listen to every out of market game, not just Boston but all 30 teams, spring training, postseason, and all games are archived for play at sane hours if you happen to live in, say, England. A baseball nut can fill his summer with it nicely with hundreds of hours of entertainment for $20/year.