// There are two ways that I can see to export this functionality to the chrome.
// 1.) We can modify InstallTrigger.install
// 2.) We can create a new function called InstallTrigger.installToDir

// Here's an example of option 1

xpi = {'CD_Ripper': { URL: 'cdrip.xpi', HASH: blah, DIR: "file:///path/to/directory"} };
InstallTrigger.install(xpi);

// Here's an example of option 2

xpi = {'CD_Ripper':'cdrip.xpi'};
InstallTrigger.installToDir(xpi, "file///path/to/directory");