I'm walking through the process now....and have found this site helpfule for the general install
Scriptful » How To Install Pligg Beta 9.6
One thing I can't seem to find are the Cache and templates_C folders to CHMOD
I understand it's for an older version but
HowToTuts.com - Great free how-tos and tutorials! suggests * In 6th step, you have to also CHMOD languages directory to 777.
* In 7th step, don’t CHMOD /libs/lang.conf to 666.