I have been tasked with writing a simple one-time-use Metro/windows store/modern UI (whatever you want to call it now) app for windows 8; it wouldn\'t be appropriate to try
There was no side-loading of a Windows App when Chrome was installed. Browsers get special treatment, and the default browser (and only the default browser) can act as a Windows Store app if it implements the appropriate functionality.
There is a downloadable white paper about how this works on MSDN: http://msdn.microsoft.com/en-us/library/windows/apps/hh465413.aspx