Yes, but you need to be an admin. There is a tag called <verbatim>
which can allow you to insert HTML into a page, but it has limitations.
Do you have some example HTML you might use?
Basically what you need to do is create a new MediaWiki: page like MediaWiki:SWFembedded1 and put the HTML on that page. After you've done that, you put <verbatim>SWFembedded1</verbatim>
on the page where you want the content to appear.
This method is pretty simple, but doesn't really allow dynamic content or use of templates in the MediaWiki: page.
As always, the more info you give (like a link to an sandbox page or something), the easier it is to answer your question.
What, Fandyllic said.
Thanks - i don't have admin rights on my work pc so i have to buy a home one :-(