Board Thread:Support Requests - Getting Started/@comment-26938219-20150829030652/@comment-24042083-20150830140753

here I found how to generate the code. Further, you will need to create a MediaWiki page (for example named "MediaWiki:GoogleCalendarWidget") and paste the HTML there. Then you can put it on any wiki page with. See help:Verbatim tags.

BUT, MediaWiki pages are currently locked because of a recent security issue at Wikia. One told me you will need to ask for unlocking it via special:Contact.