At first I thought I couldn't do this quest until I was level 49 -- I can't do the quest to get the Shadowforge key, since it involves killing (and the NPC you have to kill is nowhere near soloable), and I can't pick the locks until my lockpicking is 250, which I can't do until I'm level 49 (lockpicking 245) and wear my +5 gloves.
But then I remembered I was an engineer.
Large Seaforium is a dropped recipe, which wasn't in the meager Maiev auction house, so I teleported to Everlook and bought the limited vendor recipe for the Powerful Seaforium Charge (which I will need for entering Dire Maul, Scholomance, etc before 60 anyway).
I tried a "dry run" with my level 50 rogue Rache on Stormreaver; my initial test of an Advanced Target Dummy and room aggro told me that I would pull two groups of 3, and that I'd need a Masterwork Target Dummy to give me enough time to blow the lock and close the massive doors to get from the East Garrison to the West Garrison (through the top of the door). My 50 rogue had no trouble stealthing to Gloom'Rel (he is also Subtlety specced, with stealth boots and panther trinket, but without +stealth to cloak). Since the cloak enchant gives Noor one more virtual stealth level, I figured she was only 3 levels below Rache, and it would be almost as easy for her...
Well, 3 large seaforium charges, 1 masterwork target dummy, 5 invisibility potions, 2 lesser invisibility potions, 8 flash powder, and about half a dozen deaths and two hours later, I found it wasn't as easy as I thought, but I finally got to Gloom'Rel and paid the quest tribute to learn how to smelt Dark Iron (and got a nice chunk of XP). I wasn't able to actually smelt any, as it's hard to vanish while in lava.
It cost me 3 seaforium charges because I initially only brought one to open the East Garrison door; I realized my mistake and had to leave the instance and make another charge to blow open the large doors, but when I got back in, the East Garrison door was closed again! I had to make a third charge to open that door again.
My stealthing wasn't sufficient to get past all the areas I need to go through, so I was forced to use Invisibility potions, which have a common 10-minute cooldown (you used to be able to take the "other" Invisibility potion 2 minutes later, just due to the global potion cooldown, but now you can't). It also took me 3 tries to pick the Grim Guzzler key from Plugger Spazzring, but at least I never died those times.
It's notable that this is, so far, the only time I've needed to use Seaforium to open doors, and Invisibility potions. Probably not the last, though.