Call Perl script from Thunderbird Javascript

Question

I wrote a perl script that handles some data automatically. However, I face a problem when I try to call the script from my thunderbird extension that is naturally written in javascript.

var file = Components.classes["@mozilla.org/file/local;1"]
                     .createInstance(Components.interfaces.nsILocalFile);
file.initWithPath("/usr/bin/perl");

// create an nsIProcess
var process = Components.classes["@mozilla.org/process/util;1"]
                        .createInstance(Components.interfaces.nsIProcess);
process.init(file);

// Run the process.
// If first param is true, calling thread will be blocked until
// called process terminates.
// Params are used to pass command-line arguments
// to the process
var args = ["package/myperlscript.pl", "some arguments];
process.run(true, args, args.length);

I guess I have the perl script placed at the wrong location. I tried various ones, but I could not get it work. If that is my major mistake, where is the base path that the javascript file expects?