From Apache OpenOffice Wiki
Come join the collective! Bots for new platforms or adding bots for for existing platforms will increase the build capabilities available, and are therefore much appreciated.
What you need is a reasonably fast machine, with decent RAM and disk, and of course a stable internet connection. It might be easier to first set up the openoffice build environment on this machine.
Please see http://code.google.com/p/ootermite/wiki/AddNewBuildBot for more information.