I made a seriously wacky conversion, the painting isn't close to done, but here he is anyway:

I figured he needs some rules, so this is what I've came up with so far.

Saikai may join a Tau army, (Not with the Farsight guys though) as an elites choice.
Sv: 5+

I haven't figured out his wargear and special rules yet, but I have a little backstory:

Just before the Old Ones perished, one of their humble servants was entrusted with a message along with the will of the Old Ones and put in a special capsule and frozen in the warp until the 41st millenium, the capsule fell out of the warp and crashed onto a uncharted planet close to the Tau Empire, upon meeting a Tau exploration force, he worked with the pathfinder teams and tracked down an Ork camp, drawing on the knowlegde the Old Ones had left him, he helped the Tau wipe them out and burn the camp and the corspes away to prevent new orks cropping up again, This act made Saikai a trustworthy ally of the Greater Good, knowledgeable and a fearsome scout. The Tau were not created by the Old Ones, but were not tainted by mankinds xenophobia and widled technology like magic and also abhored the creations of Chaos....

This is where you chaps and chapesses come in, I need your help to create a sort of funny yet unique character and I'm rather stuck for ideas... feel free to drop by and help out!