Staff members promote the company and the equipment. Do those things. Make it worth the company's while to have you on their staff.
Basically, use their equipment, be successful with it, and spread the word that you believe your success is due to the equipment in your hands. Be a positive image for them. Working in or owning a pro shop, where you have direct influence over what equipment your customers buy goes a long way.
And then be the one guy in 1000 that does all those things and does get a staff position.
SH