Yes, it can (and has) been done.
http://i13.photobucket.com/albums/a2...Temperance.png
RDM/NIN + RDM/NIN.
After it's been popped, each RDM needs to take their position on opposite "indents" in the circular rooms. When standing as close to the edge as possible you can cure each other across the gap. One RDM covers Bio2(3), the other covers Poison2. Simply stand still and blink tank like you would any other mob -
leave Gravity off until Meikyo Shisui. It hits relatively fast and has double attack - so that's why you'll have to bounce hate. Luckily, any slight action pulls hate when using this strategy (Utsu, SS, Refresh, Haste - all pull hate usually). Of course you can cure each other or yourself for hate as well. Temperance will basically run back and forth between players while you whittle down it's HP - once you get the hang of it, it's pretty simple.
The complicated part can be Meikyo Shisui. Odds are that at least one Meikyo Shisui will occur while Temperance is in blunt damage mode and you'll have to deal with Optic Induration. The idea is to cast Gravity asap and kite it. One RDM will probably take at least 1 Optic Induration when it initially uses it's 2HR - if the first RDM can't get Gravity off, Temperance will probably make a beeline for the second RDM after petrifying the first. For this reason, both RDMs need to be ready to Gravity very quickly.
Now theoretically, after Meikyo Shisui wears off, it's next TP move will reduce it's TP to 0 - so one RDM will probably have to eat at least one more TP move. Another side note about Meikyo Shisui is that 3 is not the maximum amount of TP moves it can use with one 2HR - my duo partner got hit 7 times in a row with Optic Induration on one 2HR. In case both RDMs are petrified - throw on DMG Reduction gear - the petrification effect is rather short-lived.
The con to duoing this is that it could easily take over 2HRs. The first time I completed this, a LS BLM/NIN arrived to deliver shihei to my duo partner and stayed the last 30% and helped with elemental DoTs. This duo has now been successfully done by multiple RDMs in my LS. Pictures of first attempt on first page (I think @.@) of my
blog.
edit: Easier to pop with just 2 RDMs than an alliance or small party. Less bodies to haul around \:D/