Yes, it is possible, but you need to configure it through the CloudFlare Partner or you need to be on a business or corporate plan. They can configure domains through a CNAME record instead of moving name servers.
There is a complete list of partners at: https://www.cloudflare.com/hosting-partners
We use this with Creare , it allows us to configure our clients site on CloudFlare, which gives performance and security benefits without changing their name store (where it is impractical or the client does not want us), we provide this option without the need for a business plan or enterprise making it more accessible to the client.
mjsa source share