I implemented it into one of the sites my firm developed using DNN: www.grenadahotelsinfo.com

There's a tutorial on Creative DNN to implement sIRF2 on DNN that I looked at but sIFR3 is the newest version which apparently works alot better.

Here's how I did it:

1. Download and extract sIFR3
2. Put sifr.js, sifr-config.js, sifr-debug.js in the js/ subfolder of your DNN installation
3. Create a flash/ subfolder in your DNN installation folder
4. Generate the flash font files by following the directions here: http://wiki.novemberborn.net/sifr3/How+to+use
5. Navigate to the DNN tab that you want sIFR on and go to the Page Settings.
6. Insert the script calls into Page Header Tags. Here's what I have:
   <script src="http://www.grenadahotelsinfo.com/js/sifr.js" type="text/javascript"></script>
   <script src="http://www.grenadahotelsinfo.com/js/sifr-debug.js" type="text/javascript"></script>
   <script src="http://www.grenadahotelsinfo.com/js/sifr-config.js" type="text/javascript"></script>
7. For the CSS, I guess you can stick the calls into the same Page Header Tags but I put it into the Portal CSS so I can access it thru the portal itself. It required a little modification. Here's what I have:
   
   /* ===sIFR===*/
   @media print
   {
   .sIFR-flash {
    display: none !important;
    height: 0;
    width: 0;
    position: absolute;
    overflow: hidden;
   }
   .sIFR-alternate {
    visibility: visible !important;
    display: block !important;
    position: static !important;
    left: auto !important;
    top: auto !important;
   }
   }
   
   @media screen
   {
   .sIFR-flash {
    visibility: visible !important;
    margin: 0;
    padding: 0;
   }
   .sIFR-replaced, .sIFR-ignore {
    visibility: visible !important;
   }
   .sIFR-alternate {
    position: absolute;
    left: 0;
    top: 0;
    width: 0;
    height: 0;
    display: block;
    overflow: hidden;
   }
   .sIFR-active .sifrhead {
         visibility: hidden;
         font-family: Trebuchet MS, Tahoma, Arial;
         font-size: 23px;
         line-height: 1em;
         color: #780000;
   }
8. I specifed the CssClass property in my Title skin object to use the sifrhead style. You can use a span or a div tho or anything else for that matter.

This is a pretty basic and rudimentary implementation of it. The sIFR3 docs should explain anything I missed here but lastly, my sifr-config.js looks like this:

var aqueline = {
  src: 'http://www.grenadahotelsinfo.com/flash/aqueline.swf'
};

sIFR.activate(aqueline); // From revision 209 and onwards

sIFR.replace(aqueline, {
  selector: '.sifrhead',
  wmode: 'transparent',
  css: {
   '.sIFR-root': { 'color': '#780000' }
  },
  fitExactly: 'true',
  tuneHeight: '-36',
  offsetTop: '-16',
  ratios: [11,3.13,13,3.04,17,3.03,25,3,26,2.98,28,2.99,50,2.98,62,2.97,86,2.96,90,2.95,91,2.96,93,2.95,94,2.96,100,2.95,103,2.96,2.95]
});

/*
sIFR.debugMode = true;
sIFR.debug.ratios({ src: 'http://ghta2.modone.net/flash/aqueline.swf', selector: '.sifrhead' });
*/

Let me know if you get thru.