Use the anonymous CVS server to get the up to date source code and documentation:
cvs -z3 -d:pserver:anonymous@cvs.sv.gnu.org:/sources/paparazzi co paparazzi3
CVS-disabled users can download a nightly tarball from this website.
A live CD to run Paparazzi is available from the same place. Boot your favorite PC with it and you get all the required tools to use the code.
There is a debian repository containing sarge packages for all dependencies there too.