Distributing a render among several computers

I’ve got a blend I want to render at a big size in Yafray. Estimated time is about 120 hours.
I’d like to use a pair of computers during several nights, for example dividing the renders in 12 parts (10 hours each).
How can I do this? Is there a way to select a precise area to render? (specifying the exact pixels, instead of selecting the border with Shift-B?)
(Please excuse my English)

if it is multiple frames, build you own render farm. search this forum for previous threads on “build render farm”. If it is just one frame, you have to set up a frameserver, but I do not know how to do that.