Installing xpi from outside Netscape. HELP PLEASE!

Hello, 

I am trying to do an administrative install of product that installs
via an xpi.  Problem is, I can't go logging in to every machine and
opening netscape, navigating to the file and installing it.  I need to
be able to run some program like an executable not within netscape and
have it install the xpi file.  When I double click on the install.js
file it gives me an error about an object being expected.  I geuss
running it within netscape sets up some library paths.  Is is it
possible to create an executable from an xpi? your help is greatly
appreciated.

thanks
steve