Hi,
You cannot paste server controls into html content, you can only put html there.
The cycle plugin is built into the Html feature so you don't need to add SlidePanel anyway, and you cannot put any server tags like SkinFolderImage into the html content.
All you need to do is enable the slideshow in settings and it will rotate the top level html elements in the content. Click the help links in settings for more info.
Hope it helps,
Joe