The Street reported Bill Ackman, who leads hedge fund Pershing Square Capital Management, late Friday appealed to institutional investors in his boardroom battle at ADP (NASD: ADP), urging the payroll processor to set up an election system giving shareholders more flexibility to pick among dissident director candidates and incumbent board members. Ackman is seeking to elect a slate of directors to the Roseland, NJ-based provider of professional employer organization, payroll and other services at the company's upcoming annual meeting. He claims the company’s success has caused it to grow lethargic and that it is underperforming its potential.