Hi,
You do not have to set any registries. EO.WebBrowser will automatically load plugins in the following directory:
1. The same directory of EO.WebBrowser.dll;
2. The directory pointed by this property:
http://www.essentialobjects.com/doc/6/eo.webbrowser.runtime.additionalpluginsdirs.aspx3. FireFox plugin directory if FireFox is installed on your system;
4. Plugin in at the following registry location:
HKEY_CURRENT_USER\Software\MozillaPlugins
HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins
#1 and #2 would be the easiest way. #2 might be better if the plugin involves many DLLs thus it could be better to put them in a separate folder. We do not know any details about XBAP plug-ins though, so you will need to contact them to find out exactly what files are needed. You can use Chrome to test whether you got all the files and once you got that working, copy them into a folder and set Runtime.AdditionalPluginsDirs property, then it will be loaded by EO.WebBrowser.
Hope this helps. Please feel free to let us know if you still have any questions.
Thanks!