Talk show host Rosie O'Donnell will join the new Broadway musical Seussical as the Cat in the Hat for four weeks beginning Jan. 16. O'Donnell who made the announcement on her show Wednesday will sub for vacationing Cat David Shiner. "Rosie wanted to do the role," Lynn Ahrens, who co-wrote the Dr. Seuss-inspired musical, told The Associated Press. "She obviously can't do eight shows a week or commit to a year. We adore her, and she loves the show. It's the kind of role a personality can come into and do for a short time." Broadway's No. 1 fan last seen on the Great White Way as Betty Rizzo in Grease will do six performances a week, while Shiner's understudy, Bryan Batt, will portray the Cat during the Saturday and Sunday matinees. O'Donnell will donate her salary to charity.