Personally, I'd enjoy being on Roto's staff, but I don't have much influence on people's decision to buy certain equipment. The pro shop owner I visit most, because me and him are friends, is on Ebonite Staff so there's no getting him to push Roto Grip. Besides, and this might be another subject altogether, wouldn't being on a certain company's staff sort of turn people away from that company because of the staffer's incentive to push that company's products? Of course there's the flip side of it where maybe the customer would think the company is really good if someone is willing to commit to them.
Other than working in a pro shop, I guess one of the other few ways to get the company some attention is to bowl in a lot of tourneys using their balls. There's also advertising like wearing their shirts or logos.