The skunk generally doesn't want to spray. It takes time for the skunk to make it and will generally only use it if it feels like its in serious danger.

I was out riding my bike once at night and I saw a skunk in front of me. I braked as hard as I could. I managed to stop about a meter from it. Little one hissed and I grabbed my bike and crossed the street.

Anyway, I figure anything you could do to convince a skunk to spray you would border on/straight up be animal abuse.