Cross-campaign unique secondaries

How does this work?

I have a Tyrian warrior who's still slogging through Maguuma Jungle, but HAS completed Sunspears in Kryta and can go to Elona. I want to switch 'em to /Dervish. Do I have to both do Tyrian ascension AND the Command Post quests (to get Elonian profession changer), or just the post quests?

just the posts, or get to senji

You could also go to Great Temple of Balthazar and change professions there, but I'm almost certain you need to be ascended first.

acension (chapter one) will not let you change to dervish. You can only change to the 6 core ones there. Senji I believe will let you change to any core and the 2 factions professions....to get /dervish you would need to do the command post in Kourna where you can change to the core (and I am not sure if you can change to the factions ones...I would need to check that out) as well as the nightfall classes.
So slog on over to the command post!

need to ascend before can change secondaries, doing the command post only applies for NF characters

do you have to be ascended even if you load into someone elses command post? Like say I was not ascended but my friend was...so i let him lead the party to load his "version" of the post...can i not use the proffession changer then?