Make it fun. Target kids that don't fit in with other sports-the skinny ones, the small ones, the ones who lack fine motor skills. You also might look at the 3rd stringers from other teams-football, soccer, etc. There will be some good runners in these groups. Even if they aren't great-some of these kids will be glad you asked them, and work their tails off. You never know where your talented kid will come from-my school had a state champ who started running as a Junior-prior to that he smoked a lot of marijuana. He joined the team because it looked like the kids had fun. In your recruiting, emphasize the co-ed nature of the sport (I'm assuming the boys and girls practice together at your school) That is a very valuable tool in recruiting.
If the rules in your state allow, have a fun run once or twice a week over the summer with these kids. Build an esprit de corps. Saturday morning 5 miler, with a donut and orange juice buffet at the end is always popular. Structure you team around the social aspect-the running will follow. Teach them the reasoning behind long runs, intervals, and tempo. Kids are smart. Painful interval sessions aren't so bad if they understand the purpose.