I haven't heard yet of a sure way to find him - you just have to get lucky and be playing when BNET craps him out.
He is not that hard to kill if you max out your resistances. Dwarf Star rings and rising sun ammy help alot - fire absorb bonuses from them help. My Paly whooped his ass pretty easy - just takes time - he has a shitload of Hitpoints. if your resistances are low you will probably not be able to kill him by yourself
for dc info, he is like lvl 110, 95 all resists, his fire hose does half physical and half elemental dmg and he cant do like other new spells and shit, they say on arreat summit is is wise to have a lot of fire and light asorb and physical dmg reduction, im guessing he is freakin insane to kill