You can point a custom domain to any event. For example, if your event was “UltimateConf” you could point tickets.ultimateconf.com to your registration page.
To do this, click on “Customize”, and then “Edit” under “Basics”. Fill in your desired custom domain.
Now, you need to create a CNAME record that points to ti.to for the domain you specified.
We recommend our friends at DNSimple for domain registration.