Marquee

Marquee is HTML - you can't change that.

Another option is to use an animated image....

Or you could use a Widget in the Sidebar, here's one that works well in the sidebar

http://www.widgetbox.com/widget/scrollfx-1-0-std

Visit the site and customise the text and style then copy the code. You may need to adjust the width to fit your sidebar but it works. Trim down the code and add a </embed> at the end to make it work.

Here's code that's tested on Lefora

<embed src="http://widgetserver.com/syndication/flash/wrapper/InsertWidget.swf"  name="InsertWidget_d567cc4a-e777-4c23-826e-accc14710358"  width="250px" height="63px" quality="high" menu="false" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" wmode="transparent" align="middle"  allowScriptAccess="sameDomain" flashvars="r=2&appId=d567cc4a-e777-4c23-826e-accc14710358" /></embed>

See it in action here.

Thank you very much.