HI,
Can you please try the solution provided @ http://answers.splunk.com/answers/10501/python-script-as-unarchive-cmd-in-props-conf.html
Also, you can take a look @ http://blogs.splunk.com/2011/07/19/the-naughty-bits-how-to-splunk-binary-logfiles/ for parsing using perl script.
Thanks !!