The last few times I did it, I just showed up where it takes place, and there were multiple other people already there.
Make sure to go there OUTSIDE of Chromie Time. If you are in Chromie time, not only will there likely be no one there due to phasing, but even if there is someone there, the content will scale to them as well and it will still be extremely difficult.
If you go there in the current timeline during peak hours, the mobs only go up to like level 30, and more often than not someone else will be there with a max level character. Since the event is only once every two hours, everyone that needs/wants to do it has to go there at the same time.
Last time I did it, I just chilled by where the vendor spawns and let the max level players do it, you don't need to be in their group or even participate. The vendor will spawn as long as anyone completes the event and kills the elite.
Of note, you can also just group in with anyone 40+ outside of chromie time and it should be easy.
Since the TBC portals do not function at 11 outside of Chromie Time, you will either need to set your hearth somewhere in Outland, or use another method like the Fractured Necrolyte Skull.
