If you are not having balance problems, figure out where you should slide and put a shoe cover to the left of where your foot will end up if you slide toward your target. All you have to do is don't hit the shoe cover when you slide.
One other thing might be that you are leaning to the right when you are going into your slide. I have a teammate that does this, it doesn't seem to matter how far inside he moves his feet, he still hits between the 15, and the 10 board at the arrows, with the same laydown point. If this is your problem, try to keep your posture upright and centered over your belt buckle. Make sure you are getting your ballance arm out on the second step and keeping it up, not letting it drop to your side.
The last thing to try is have someone watch you from behind (your coach or watch your video tape yourself). What you are looking for is your swing plane. Your swing could be starting infront of your body, falling back to the right and looping back toward your slide foot, but not far enough, or it could be pushing to the right, swinging back behind you and looping out to the right on the down swing. If you are having this problem, check out Ron Clifton's articles on swing plane in his archives tips 43 through 45:
http://www.bowl4fun.com/ron/roncarchive.htm
