Is the compress directory even used in your version?
Anyway, here's a Linux version named bzip.sh, although it does require the Bash shell as it uses bash constructs such as GLOBIGNORE.
Apparently you can't attach bz2 files on AlliedModders. Which is a shame as generally Linux distros already have them installed.
Note that this Bash script makes a copy of the files before compressing them. It was either that or do it in place and move the bz2 files after the fact... which would create problems if you had other bz2 files already around.
Code:
#!/bin/bash
GLOBIGNORE="./bzip.sh:./compress"
if [ ! -d compress ]
then
mkdir compress
fi
cp -r ./* compress
find compress/ -type f ! -name "*.bz2" -exec bzip2 {} +