Hi,
On my old account (75 WHM / 75 BLM on Remora Server) I used to camp Cassie a fair bit, mainly because me and a small group of friends were the only people to know the ToD. (Also got 2x cape + 3x earring in 1 week :D). Our strategy varied each time because of the party setup. Usually, we would go like this:
WHM (for Raise 3, is pretty much a must if you want that exp back . Also, WHM with BLM sub can land bind almost 100% of the time if you are kiting)
RDM (for gravity and bind)
(possibly another RDM)
2 out of BLMs and RNGs (obvious reasons)
THF (treasure hunter)
WAR or NIN (to try and kite).
When we were kiting Cassie, the melee's would build TP on the surrounding mobs then do 300% WS's on her. The mage's would follow and bind and gravity as much as possible. We would always try to keep 1 mage out of sight of cassie in case of Bad Breath. This strategy is pretty good, provided you're either alone, or the only other campers are trustworthy not to steal claim. This method usually took us about half an hour to kill, with a party of 6. It's pretty simple and does not require much in the way of tactics, but does take a long time. It can possibly go to shit if cassie BB's and kills most of the melees or mages ;p.
The other way we would sometimes do it would just be a NIN blink tanking, but not attacking. Then the other melee would WS as before. It was possible to SATA with the RNG and THF which kept hate stuck on the NIN. In the event of a BB, the NIN would have to hope he can remove silence either from a mage, or with oils. I'd estimate about 75% of attacks missed, were parried, or cassie was paralyzed, which means even if cassie does BB, the NIN won't take lots of damage quickly. This is a safer method imo, and if you feel like it the NIN can attack Cassie in order to keep it claimed.
It's not a difficult NM to kill, I've witnessed a NIN and WHM solo it (very slowly, mind). But the above configuration is my recommended approach.