When I had figured out what the different privileges and consequences would be on the chart, I sat down with all of the children who were going to be on the chart, and explained it to them. Along with laying out the consequences, we talked about what the rewards would be, and I asked them what sort of rewards they would like to be able to earn. When we were finished talking, I asked them questions to make sure they understood what I had told them, and I gave them one practice day where I would say, "When you are on the chart, you will _______ when you _______." to help them get used to the idea.
I have kids who have been known to have a COMPLETE MELTDOWN (screaming, kicking, throwing things, breaking things) when they get moved down the chart, especially when they do something to get moved directly to the bottom. And I knew that Ian was likely to try to destroy it the first time he got mad about it, so I talked to him about that situation BEFORE it happened, during a moment that he was calm. I decided what the consequences would be if he ripped the chart to pieces, told him what the consequences would be, and prepared myself to follow through if it happened. For Ian, the consequences would have been watching his younger siblings while I made a new chart, which would have been something he HATED, but for Joseph--my current Meltdown Child--if he destroys the chart, he will lose all privileges for an entire week (INCLUDING food, so he would get to eat oatmeal, fruits, and vegetables for a week).
I heard, early on in my parenting career, someone say something about NEVER telling your child you're going to do something unless you're really going to do it, and I have tried very hard to follow that advice. I HAVE followed through on tough consequences before, so my children knew I was serious when I laid out the chart-destroying consequences, and, so far, neither of them has done it (but I wouldn't be surprised if Joseph does sometime soon because he seems to be ITCHING to find out how far he can go/if I'll enforce the consequences). They've kicked the wall the chart is on and slapped it hard when they're moving their marker, but they haven't ripped it up.
There is an adjustment period whenever you start a behavior modification program; your child will test the limits and your patience while he tries to determine how serious you are about this, so, if you think it is a realistic possibility that he will destroy the chart, it is very likely that he WILL the first time he gets really mad about it. Since you know that is likely to happen, expect it, and figure out NOW what the consequences will be, and be prepared to stand by them. You could even have another chart already made so that, once he's calmed down, you can matter-of-factly put a new one up. It will help you hang in there, and him to realize that you're serious, if you just plan on having to replace the chart 10 or 15 times. The key is to do it CALMLY every time; if you can stay calm, it helps him get the message that YOU really are the person in charge, and you are planning on sticking to your guns.