He couldn't fit that Charmed gig into his busy sked, but singer-cum-Extra host Mark McGrath has found time to co-emcee (alongside Without a Trace's Poppy Montgomery) CBS' Fashion Rocks special next month. Billed as a celebration of the "best in fashion and music," the two-hour event will be taped Sept. 8 at Radio City Music Hall for airing the following night on CBS hence, Poppy's involvement.