Call to Lordaeron was available to my level 60 blood elf mage upon logging in after the 9.2.5 update.
There are certain new questlines in this update purportedly only available to elves or hunters, but from the diverse other races and classes who appear to be on this quest in the phased version of Brill, this particular quest appears to be available to all characters at level 60.
Go to the southwest quadrant of Oribos to find [npc=173386] to start the quest, then talk to the Forsaken Dreadmage standing nearby to teleport to Brill.
EDIT: this questline is available to all characters at level 60 who have chosen a covenant. You can do the questline on any race toon, and upon completion you will unlock the Dark Ranger elf customizations for all elf characters on your account.
To unlock the hunter transmog, you MUST complete the questline on your hunter toon.
After you complete the last quest in the storyline, you get the Return to Lordaeron achievement and the [title=720] title.
Then all blood elves, night elves, and void elves on your account will have access to the Dark Ranger customizations. This means that when you go into the barbershop, you can choose red eyes and gray skin for your elf characters.
If you got the achievement on your hunter (doesn't have to be an elf), you can then go to your Legion class hall and purchase [item=191658].
You can do the questline on multiple toons on your account. So if you did the questline first with a non-hunter, just redo it with your level 60 hunter to get access to purchase the hunter transmog. If you completed the questline with a non-elf, you still get access to the elf customizations anyway. Log into an elf character and go to a barbershop to get red eyes WITH gray skin (currently if you select the eyes, the skin tone comes with it automatically, and vice versa).