First, you should have your own tracking domains, then going to these tracking domains service and resolving to FuseClick default tracking domain by CNAME method.
Second, you need to go to “Setup -> Settings -> Tracking Settings -> Tracking Domain -> Manage Tracking Domains -> Add Tracking Domain” to add your own tracking domains.
Now FuseClick supports to add at most 10 customized tracking domains, and all domains can be effected at the same time. And you can set any one as default tracking domain.