When looking for a writing tool it is important to go from direct access to alternative format. For example, you say you have CP. But you do not say what your ability is to type. I am going to assume that you typed this question to Yahoo! answers. If you have the ability to type then I would also assume that you can use a standard keyboard with success. If that is the case, then I would suggest that you look for tools that may help you with typing such as word predication software. “Word prediction aids individuals with limited keyboarding ability and can be used with standard application software. It is also useful to support spelling and grammar skills. As characters are typed, the word prediction software revises a “pick list.” When the desired word or phrase appears, it can be selected and will automatically update what is being typed.” This type of software picks up the speed of writing.

Depending on your country, state and age you maybe able to get services through your college or division of vocational services if you are out of school.

Below is a link to a person that has CP. She talks about her accomplishments and frustrations.