After step 2, log onto another character that does not have the eradicator set. Find the eradicator armor and mask in the "Armor" section of the collection interface. An icon will show up in that character's collection to the right of the Cartel purchase icon. Click on it, and unlock the armor (I think it will cost 600 CCs for eradicator's), then click on the unlock button for the mask and unlock it with Cartel Coins.
When unlocked, a small blue icon that looks like three people will show up on the right, middle-ish side of the collection item. That means you have unlocked the item for your entire account. You will now be able to make as many copies of the eradicator set, on any of your tunes, on any server as much as you want.
*signed*