Something

#!/bin/bash
package='thunderbird-2.0.0.9-i586-2vl59.tlz'
mkdir explode
cd explode
explodepkg ../$package
cd ../
size=$(du -bc explode | grep total | sed 's/	total//')
installpkg $package > /dev/null 2>&1 &
until [ -e /var/log/setup/tmp/fifo1.* ]; do
   sleep .001
done
fifo=$(ls /var/log/setup/tmp/fifo1.*) #pv or cat won't accept fifo1*
./pv -i 0.1 -s $size $fifo > /dev/null