К сожалению это не возможно, официальная позиция Майков по этому вопросу -
msdn.microsoft.com/en-us/library/windows/apps/hh46...
"WWAHost.exe cannot host Adobe Flash Player objects. If a Flash component is essential to your web app, you must port the Flash object to HTML/CSS and JavaScript. HTML5 and the Windows Runtime provide some of the lower-level OS and user interface (UI) functionality you need to accomplish this."
