You can't do that. The child tax credit is the only benefit of claiming a dependent that can be transferred to the non-custodial parent. (Other benefits of claiming a child as a dependent, like EIC, the dependent care credit, and head of household status, can only be claimed by the custodial parent and can't be waived, transferred or shared.)
Perhaps your custody order instructs you to do something that is not allowed under federal tax law (federal law always trumps state court orders). This might be something you need to review with your attorney.
Can you explain your situation more? Maybe we can help you with better information if we know more about the situation.
