Sorry if this is a repost, I just thought of this.
You cannot be 80 as you can enter heroics. You cannot have any keys for TBC heroics.
This is only for level 58-79s, and isn't hard to do.
So, all you need to do is to queue up for a random dungeon and die.
Release spirit, and leave group.
Set dungeon to 5 man heroic, then run back to the instance.
It should give you a message "Heroic Difficulty requires the <Instance> Key, or level 80.
You shouldn't have any keys for heroics so you can easily get to Hellfire from somewhere, or etc.
So you can queue specifically for Violet Hold when you are of level, and do the above.
TLDR:
[spoiler]Die in instance, leave group, set 5 man heroic, enter instance, profit[/spoiler]