HOLIDAY WEEK, PART 2: Bryan Atchison and Neil Olstad were college roommates in Winona, Minn. Now they’re stagemates wherever they can set up two microphones and an iPod. Koo Koo Kanga Roo, caught here as part a bill at the Varsity Theater, are putting on an all-ages Koo Koo Kanga Roo Kristmas — a production complete with a plotline — December 18 at the Varsity.