XPInstall API Reference:InstallTrigger Object:Methods

[edit] Methods

compareVersion: Compares the version of a file or package with the version of an existing file or package.
enabled: Indicates whether or not the Software Installation is enabled for this client machine.
getVersion: Returns an InstallVersion object representing the version number from the Client Version Registry for the specified software or component.
install: Installs one or more XPI files on the local machine.
installChrome: Installs new skin or locale packages in Netscape 6 and Mozilla.
startSoftwareUpdate: Initiates the downloading and installation of the specified software. Note: Deprecated in favor of install.