Boomboxes can now only be obtained by playing on the Wildstar test server (PTR) when Carbine is requesting for assistance in testing a new feature. They will announce what days are eligible to be earning boomboxes on their forums and what activity they would like you to participate in (Daggerstone Pass, Blighthaven Quests). Unfortunately there is no set days where you can earn boomboxes, it is based entirely off of Carbine's announcements.
In regards to Deluxe Owners getting Boomboxes, I believe they are referring to that if you pre-order you got access to the beta, which gave you 3 boomboxes per day of logging on.