Unzip the Particle Universe package in ../ogrenew
This creates ../ogrenew/PlugIns/ParticleUniverse, which includes the sourcecode and the documentation.
Also the viewer application ParticleUniverseViewer is created in ../ogrenew/Samples and the Particle Universe media is created in ../ogrenew/Samples/Media/ParticleUniverse

Add the entry Plugin=ParticleUniverse to Plugins.cfg

Add to resources.cfg the following entries:

FileSystem=../../../Media/ParticleUniverse

FileSystem=../../../Media/ParticleUniverse/material

FileSystem=../../../Media/ParticleUniverse/scripts

FileSystem=../../../Media/ParticleUniverse/models

FileSystem=../../../Media/ParticleUniverse/gui

FileSystem=../../../Media/ParticleUniverse/textures/32x32

FileSystem=../../../Media/ParticleUniverse/textures/64x64

FileSystem=../../../Media/ParticleUniverse/textures/128x128

FileSystem=../../../Media/ParticleUniverse/textures/256x256

FileSystem=../../../Media/ParticleUniverse/textures/various