Saw her twice last night. We didn't do anything special to make her spawn, so leave the voodoo dolls at home, guys. :P
The best way to get to her is to cross the bridge that's the first left from the window room area. I was using the map from eqatlas, and it was easy to find the way to the front of the courtyard where EXG spawns. Having been the back way, as I guess you could call it, where there's about a million more gnome fights, I highly suggest this route instead.
Anyway, get past the gobbies (by invis, if you're lucky and there are no shammies/wizzies, or just by fighting), and you'll eventually find some more gnomes. There were a few adds at times, but I don't remember there ever being more then 1 to mez. The spawns are also pretty well spaced out, so you should be able to rest up right where you are, until you're ready to move on.
Once you enter gnome country, be aware that EXG can wander this area, so keep your eyes open. This will be a good thing if you can handle it, as she drops the charred guardian shield/ breastplate. She sometimes brings another gnome robot friend, which can make things a bit hectic, so be ready with your mezzes or roots or extra tanks. We got 2 shields and 1 breastplate in 2 hours over here, so don't see her once and think you're safe. :P
So move up slowly but surely, and you'll reach the courtyard. If you peek around the corner before you move, you should always be able to react before the mob does, which is nice. Nothing like "What's over here..." and getting jumped on. :)
When you get to the courtyard, there are 2 spawns on either side of the gate, and oftentimes a wanderer past the iron bars, as well. Kill them. At this point, if Gabbie is up, you'll be able to see "Gabbie Mardoodle begins to cast a spell".
If she is up, get buffed up. Magic resist is essential. We saw her twice. The first time, she came with 1 add, and the second time, she came with 2. She had a DS on both times (as did her companions), so dispel it asap, as it can add up quickly. Her spells hurt a lot, too, so be ready. We didn't have a healer, and the SK does steady but not extremely fast dmg, so I alternately stunned her and runed him. For a blue caster, she had a lot of hits, too.
We killed her and she dropped the cloak (which isn't lore), but I was very low on mana and the SK was low on health. We sit and rest a while, and are talking about pulling the tunnel the way we came to get out, and then we see her casting again. That time she only dropped the quill (if she has it, she'll use it).
We decided to log then, but we could've stayed quite a while. There's two possible drops over here (EXG and Gabbie), and if you want to exp, just backtrack up the tunnel and keep yourself sated on gnomes.
Good luck to all who try her!