http://wiki.answers.com/Q/How_can_you_play_on_the_nationwide_PGA_golf_tour
http://www.ehow.com/how-does_4842329_becoming-golf-professional.html
I'd also say that if you're playing well enough you could write off to the many golf sponsors, request sponsorship and show them how good you are. Golf sponsors know where to put up their own advertising to make sales so it's likely they'll also know of other avenues into playing on the PGA Tour, starting with the Pro Ams I believe.