You are welcome to point multiple domains to a single liveBooks site. Usually there are two situations you will be doing this for:
#1 - Temporarily point old domains to your new site with the plan of retiring them in time.
If you plan to move away from the alias domains in time, please contact your domain registrar and them create a 301 redirect for that domain pointing it to the primary domain. When you are ready to phase these domains out, simply stop paying for hosting / registration.
#2 - Permanently push multiple domains to your primary domains.
If you plan to keep the alias domains in perpetuity, please contact your domain registrar and have them set up a 302 redirect for those domains and point them to the primary domain.
For instructions on how to publish your liveBooks site fully, click here.