(Reuters) - Retail investors in U.S. human resources firm Automatic Data Processing Inc will have a chance to grill billionaire shareholder William Ackman on Tuesday, an innovative bid by the hedge fund manager to seek support in his quest for board seats.

William 'Bill' Ackman, CEO and Portfolio Manager of Pershing Square Capital Management, speaks during the Sohn Investment Conference in New York City, U.S., May 8, 2017. REUTERS/Brendan McDermid

The online questions-and-answers session, scheduled for 7 p.m. (2300 GMT), illustrates the important role that non-institutional investors - such as retirees and amateur stock pickers - could play in a spat between Ackman, the chief executive of Pershing Square Capital Management LP, and ADP ADP.O.

Ackman has been pushing ADP to streamline operations and the company’s shareholders are due to vote on Ackman’s three nominees to the company’s board on Nov. 7.

Retail investors account for 28 percent of ADP’s stock, while Ackman’s firm owns an 8.3 percent economic stake and a 2 percent voting interest.

The event will be the first time ever that a prominent activist investor has hosted a live webinar for retail investors.

For at least an hour, the 51-year old Ackman, who routinely rattles through hundreds of slides to underpin investment ideas at conferences, will face what Pershing Square has said will be unscripted questions from shareholders.

The webinar will cover issues affecting ADP and how operations can be improved, Ackman told Reuters.

“It will give all shareholders a chance to learn about how electing a large investor to ADP’s board can help make ADP a faster growing, more efficient and more valuable company,” Ackman said.

The potential impact of Ackman’s efforts is uncertain, because retail investors do not always use their proxy votes. Still, some industry insiders welcomed the move.

“This is a great new development for the proxy fight venue,” said John Lame, who runs financial advisory firm Lenox Wealth Management. “It is a good idea and would be even better if you could easily and immediately vote your shares after such a conference call.”

Ackman is already fairly well-known among retail investors, with an online investing tutorial that has been watched more than 2 million times on YouTube.

He made a public presentation last month outlining the kind of operational improvements he thinks will help boost ADP’s share price.

ADP has responded by arguing that Ackman’s aim is to control the company and replace Chief Executive Officer Carlos Rodriguez, who has called Ackman a “spoiled brat” on TV.