If you’re using Blender 2.5 or 2.6, try Yabee.
As to installation, I may be misremembering, but I think that you simply extract the zip file into the folder //scripts/addons/.
As to use, select your model, go to File->Export, select “Panda3D (.egg)” and go from there. I think that more detailed instructions may be available either in the thread linked-to above or elsewhere on the fora.