ImpressRunner is a LibreOffice and OpenOffice extension that you can use to open PowerPoint presentations automatically. In order to use this extension, the end user should install it for the first time from Tools > Extension manager > Add. If it is not installed, the process will be transparent. Once installed, any powerpoint Slideshow .PPS file will be autostarted like an Impress presentation. If a Presentation document contains a userfield property with ‘autostart’ value as string, the file will also be played automatically.
The author of this extension also added a toolbar containing 2 buttons for setting or removing this mode for Impress Slideshow designers. Displaying it is not required for end users.
You can learn more here: http://extensions.libreoffice.org/extension-center/impressrunner if you have LibreOffice or here http://extensions.services.openoffice.org/project/ImpressRunner if you have OpenOffice.