Yeah, what Rapunzel said. I would add that if you push for this person to stop cutting it will just aggravate the problem because there will be a sense of lack of acceptance of her(?) as a person. Also there is a possible addictive link to it that makes it even more difficult to quit because the craving for the act itself.

My suggestion is to set some clear boundries but first you need to decide just how much of this problem can you listen too. There are people who can't stand to hear about SI. It disgusts them on some deep level. Other people who don't cut are able to listen and understand and lend valuable support. You need to decide where on that continuum you are. If talking about it bothers you be straightforward about that in as kind a way as possible. Tell this person that you can listen to what is hurting underneath but the fact of SI bothers you. Or if you are good with the SI, tell the person she/he can talk about it but has to accept when she does you will be compelled to help her find other altenatives to coping and that you hope it doesn't bother her but for her well being it is important that she searches for new outlets. In the end however, it comes down to whether she wants to stop. If she doesn't there is nothing you can do to help her and pushing will just drive her away.
Carrie

<font color=green>But the implicit and usually unconscious bargain we make with ourselves is that, yes, we want to be healed, we want to be made whole, we're willing to go some distance, but we're not willing to question the fundamental assumptions upon which our way of life has been built, both personally and societally.--Bill Plotkin, Soulcraft