You can find it at the home page, hovering the mouse button over the latest news colum:
Just click on it and add the Slice.
And now you're subscribed to Kartones.Net last 10 posts in this "new" way * :D
About the development...
You can check the MSDN for a few basic guidelines, but I warn you you'll find by yourself that slices are quite limited.
So, basically, you will rely on creating a stripped-down version of the page you want to "slice", and use the <a rel="entry-content" href="xxxx"></a> tag to point to that working version.
I re-burned my own RSS feed (the new SyndicationFeed class of .NET Framework 3.5 is great ;) and CSS-styled a bit the content.
*IE8 Web slices smell a lot like Safari's Web Clips.