how do you get a blender plugin for Mozilla?
what do you mean? the web plugin?
get it here:
linux: http://www.blender3d.com/cms/Unix_Beta.211.0.html
windows: http://www.blender3d.com/cms/Netscape__Windows.210.0.html
there is instruction too.
but don"t expect too much, it’s not supported since a long time ago.