lol, that you are! You can actually force the browser into column view with <meta name="viewport" content="width=240"> I haven't tried using it to cap the height of the site though, instead I've used the css height property and the overflow property. (on some encapsulating div layers)
You can check out this site for more on DSi browser stuff: http://www.dsibrew.org/wiki/Nintendo_DSi_Browser