First you need to have the agent installed. (Might post an article on how to simplify that)
Then you need to create a scheduled software package or recurring task using the script below. Some of this script is borrowed from one I found and edited to work with altiris.
. `aex-helper info path -s INVENTORY`/lib/helpers/custominv_inc.sh
#
# Sample script for custom inventory
# The first line of code should be always included at the begin of the script
# Actual script for collecting inventory data begins after the following label:
# SCRIPT_BEGINS_HERE
#!/bin/sh
echo Filevault2Status
echo "Delimiters=\"%\" "
echo string256
echo FileVault_Status
CORESTORAGESTATUS="/private/tmp/corestorage.txt"
ENCRYPTSTATUS="/private/tmp/encrypt_status.txt"
ENCRYPTDIRECTION="/private/tmp/encrypt_direction.txt"
# Get number of CoreStorage devices. The egrep pattern used later in the script
# uses this information to only report on the first encrypted drive, which should
# be the boot drive.
#
# Credit to Mike Osterman for identifying this problem in the original version of
# the script and finding a fix for it.
#
DEVICE_COUNT=`diskutil cs list | grep -E "^CoreStorage logical volume groups" | awk '{print $5}' | sed -e's/(//'`
EGREP_STRING=""
if [ "$DEVICE_COUNT" != "1" ]; then
EGREP_STRING="^\| *"
fi
osversionlong=`sw_vers -productVersion`
osvers=${osversionlong:3:1}
CONTEXT=`diskutil cs list | grep -E "$EGREP_STRING\Encryption Context" | sed -e's/\|//' | awk '{print $3}'`
ENCRYPTIONEXTENTS=`diskutil cs list | grep -E "$EGREP_STRING\Has Encrypted Extents" | sed -e's/\|//' | awk '{print $4}'`
ENCRYPTION=`diskutil cs list | grep -E "$EGREP_STRING\Encryption Type" | sed -e's/\|//' | awk '{print $3}'`
CONVERTED=`diskutil cs list | grep -E "$EGREP_STRING\Size \(Converted\)" | sed -e's/\|//' | awk '{print $5, $6}'`
SIZE=`diskutil cs list | grep -E "$EGREP_STRING\Size \(Total\)" | sed -e's/\|//' | awk '{print $5, $6}'`
# Checks to see if the OS on the Mac is 10.7 or 10.8.
# If it is not, the following message is displayed without quotes:
# "FileVault 2 Encryption Not Available For This Version Of Mac OS X"
if [[ ${osvers} -lt 7 ]]; then
var='FileVault 2 Encryption Not Available For This Version Of Mac OS X'
echo $var
fi
if [[ ${osvers} -ge 7 ]]; then
diskutil cs list >> $CORESTORAGESTATUS
# If the Mac is running 10.7 or 10.8, but does not have
# any CoreStorage volumes, the following message is
# displayed without quotes:
# "FileVault 2 Encryption Not Enabled"
if grep -iE 'No CoreStorage' $CORESTORAGESTATUS 1>/dev/null; then
var='FileVault 2 Encryption Not Enabled'
echo $var
fi
# If the Mac is running 10.7 or 10.8 and has CoreStorage volumes,
# the script then checks to see if the machine is encrypted,
# encrypting, or decrypting.
#
# If encrypted, the following message is
# displayed without quotes:
# "FileVault 2 Encryption Complete"
#
# If encrypting, the following message is
# displayed without quotes:
# "FileVault 2 Encryption Proceeding."
# How much has been encrypted of of the total
# amount of space is also displayed. If the
# amount of encryption is for some reason not
# known, the following message is
# displayed without quotes:
# "FileVault 2 Encryption Status Unknown. Please check."
#
# If decrypting, the following message is
# displayed without quotes:
# "FileVault 2 Decryption Proceeding"
# How much has been decrypted of of the total
# amount of space is also displayed
#
# If fully decrypted, the following message is
# displayed without quotes:
# "FileVault 2 Decryption Complete"
#
if grep -iE 'Logical Volume Family' $CORESTORAGESTATUS 1>/dev/null; then
# This section does 10.7-specific checking of the Mac's
# FileVault 2 status
if [ "$CONTEXT" = "Present" ]; then
if [ "$ENCRYPTION" = "AES-XTS" ]; then
diskutil cs list | grep -E "$EGREP_STRING\Conversion Status" | sed -e's/\|//' | awk '{print $3}' >> $ENCRYPTSTATUS
if grep -iE 'Complete' $ENCRYPTSTATUS 1>/dev/null; then
var='FileVault 2 Encryption Complete'
echo $var
else
if grep -iE 'Converting' $ENCRYPTSTATUS 1>/dev/null; then
diskutil cs list | grep -E "$EGREP_STRING\Conversion Direction" | sed -e's/\|//' | awk '{print $3}' >> $ENCRYPTDIRECTION
if grep -iE 'Forward' $ENCRYPTDIRECTION 1>/dev/null; then
var="FileVault 2 Encryption Proceeding $CONVERTED of $SIZE Encrypted"
echo $var
else
var='FileVault 2 Encryption Status Unknown. Please check.'
echo $var
fi
fi
fi
else
if [ "$ENCRYPTION" = "None" ]; then
diskutil cs list | grep -E "$EGREP_STRING\Conversion Direction" | sed -e's/\|//' | awk '{print $3}' >> $ENCRYPTDIRECTION
if grep -iE 'Backward' $ENCRYPTDIRECTION 1>/dev/null; then
var="FileVault 2 Decryption Proceeding. $CONVERTED of $SIZE Decrypted"
echo $var
elif grep -iE '-none-' $ENCRYPTDIRECTION 1>/dev/null; then
var='FileVault 2 Decryption Completed'
echo $var
fi
fi
fi
fi
fi
fi
# This section does 10.8-specific checking of the Mac's
# FileVault 2 status
if [ "$ENCRYPTIONEXTENTS" = "Yes" ]; then
if [ "$ENCRYPTION" = "AES-XTS" ]; then
diskutil cs list | grep -E "$EGREP_STRING\Fully Secure" | sed -e's/\|//' | awk '{print $3}' >> $ENCRYPTSTATUS
if grep -iE 'Yes' $ENCRYPTSTATUS 1>/dev/null; then
var='FileVault 2 Encryption Complete'
echo $var
else
if grep -iE 'No' $ENCRYPTSTATUS 1>/dev/null; then
diskutil cs list | grep -E "$EGREP_STRING\Conversion Direction" | sed -e's/\|//' | awk '{print $3}' >> $ENCRYPTDIRECTION
if grep -iE 'forward' $ENCRYPTDIRECTION 1>/dev/null; then
var="FileVault 2 Encryption Proceeding. $CONVERTED of $SIZE Encrypted"
echo $var
else
if grep -iE 'backward' $ENCRYPTDIRECTION 1>/dev/null; then
var="FileVault 2 Decryption Proceeding. $CONVERTED of $SIZE Decrypted"
echo $var
elif grep -iE '-none-' $ENCRYPTDIRECTION 1>/dev/null; then
var='FileVault 2 Decryption Completed'
echo $var
fi
fi
fi
fi
fi
fi
if [ "$ENCRYPTIONEXTENTS" = "No" ]; then
var='FileVault 2 Encryption Not Enabled'
echo $var
fi
# Remove the temp files created during the script
if [ -f /private/tmp/corestorage.txt ]; then
rm /private/tmp/corestorage.txt
fi
if [ -f /private/tmp/encrypt_status.txt ]; then
rm /private/tmp/encrypt_status.txt
fi
if [ -f /private/tmp/encrypt_direction.txt ]; then
rm /private/tmp/encrypt_direction.txt
fi