This script uses the Perl module Asterisk::AGI, which can be found here (asterisk-perl):
http://asterisk.gnuinter.net/

To install this script, just copy the .conf to /etc/asterisk and the .pl to /var/lib/asterisk/agi-bin.

The .pl should be executable for Asterisk, so chmod 755 may be a good idea.

Most documentation can be found in the .conf.

Additionally a small german documentation can be found at:
http://ip-phone-forum.de/forum/viewtopic.php?p=54821

Hope you enjoy!
-Thomas (tw (at) zentrifuge (dot) biz)
 