I got 2 out of my 3 Kazham Keys solo as a WHM. Giddeus took me about 2 hours and over 30+ kills (also competing with higher level players who were farming chests) but I got it.
A note to WHMs who try this in the future, Yagudo Priests are a bit tough as a WHM as they are a bit harder to silence (and can silence you if you fail >.<). I found casting Silence first on Theologists made them a piece of cake, and Slow turns Yagudo Votaries (MNK class) into sissies.
Sub BLM and use Blaze Spikes all the time, that extra 7+ damage to the mob every time you get hit is very handy, as is Drain.
Palborough was a little bit easier since I got the key off of the fourth target Quadav I killed, and had no problems sticking any enfeebles. Of course on the way out my Sneak ran off in the middle of a nest and I ended up getting killed when I trained like 10 of them, but it's okay, I got my key!
Now if I can just find a party in Yuhtunga Jungle. It's amazing how non-WHM friendly a lot of these level up places can be!