Multisite with domain mapping through Cloudflare

I have a Multisite Network that I have tried to get to work though Cloudflare. My questions are the following:

How can I have it working with Domain Mapping so the user doesn't have to register his website on Cloudflare?
If the domain is pointed to CloudFlare nameservers the traffic will be re-routed automatically.
I am trying to find a way not to force the user to point his domain to CloudFlare nameservers.