You can use the bash script from here (old version) or here (new version) to install all needed punkbuster files and also to get an ETKEY if noone is available.

This is the content of the script

#!/bin/bash

## Copyright (C) 2011 Misanthropos - Deploy Mortar!
## pbupdate - for Wolfenstein - Enemy Territory
## combined with ETKEY get script

PBZIP=et_linux.zip
PBHOST=www.etkey.org
PBPATH=~/.etwolf/pb

wget "$PBHOST/$PBZIP" -O ~/$PBZIP

if [ -f $PBZIP ]; then
    unzip ~/$PBZIP -d $PBPATH
    echo "Punkbuster updated."
    exit 0
else
    echo "Punkbuster update FAILED!"
fi


ETKEY=~/.etwolf/etmain/etkey

if [ -f $ETKEY ]; then
    echo $ETKEY already exists!
    exit 0
fi

wget -O etkey.new http://etkey.org/distpb.php 

mv etkey.new $ETKEY

if [ -f $ETKEY ]; then
  echo ETKey generated successfully.
else
  echo Oh oh... ETKey NOT generated!
fi

A new version of the script was sent to me

#!/bin/bash

## Copyright (C) 2011 Misanthropos - Deploy Mortar!
## pbupdate - for Wolfenstein - Enemy Territory
## combined with ETKEY get script

PBZIP=et_linux.zip
PBHOST=www.etkey.org
PBPATH=~/.etwolf/pb

wget "$PBHOST/$PBZIP" -O ~/$PBZIP

if [ -f ~/$PBZIP ]; then
    unzip ~/$PBZIP -d $PBPATH
    echo "Punkbuster updated."
#    exit 0
else
    echo "Punkbuster update FAILED!"
fi


ETKEY=~/.etwolf/etmain/etkey

if [ -f $ETKEY ]; then
    echo "$ETKEY already exists!"
    exit 0
fi

wget -O etkey.new http://etkey.org/distpb.php 

mv etkey.new $ETKEY

if [ -f $ETKEY ]; then
  echo ETKey generated successfully.
else
  echo "Oh oh... ETKey NOT generated!"
fi