WGBH says its hiring the former WTKK talkers to talk away between noon and and 2 p.m. on weekdays on its "Boston Public Radio" show. The move frees up Callie Crossley and Emily Rooney, who currently hold down the microphones then, to do other things, although the station says they'll continue to get some words in edgewise on the show. 'GBH adds that Edgar B. Herwick III will continue to contribute to the show after the changeover on Feb. 25.