You can set up a 'Protective Registration' but you have to pay an annual fee (?14.20) - details here.

"When you request 'Protective Registration', a CIFAS warning flag will then be placed against your address marked Category '0' which indicates the individual has been recorded on the CIFAS database at their own request for their protection. CIFAS members when undertaking a search against your address will see "CIFAS-DO NOT REJECT-VALIDATION REQUIRED", whatever name they search for.

As a result of the entry CIFAS members will undertake additional verification checks to ascertain that the applicant is genuine and not a fraudster trying to commit identity theft. This may mean you personally experience delays while your credentials are fully checked out."

I can understand that someone who has experienced identity theft might be willing to pay an annual fee to protect themselves in future, but frankly, when you haven't been personally inconvenienced and are just trying to help prevent commercial companies from being victims of fraud, it's a bit of a cheek to expect you to pay to register.