cname and mapped subdomain help?

My main multisite is llbh.com
we have a site at "drunkdriving.llbh.com" that we are going to domain map to "drunkdriving.com" using an a record to the ip address which should work fine.

How do i map another site "directorydrunkdriving.llbh.com" to be a subdomain "directory.drunkdriving.com" using a cname?

Will this work for both of the sites?