1) Go to your blog template editing page
2) Paste your tracking code into <head>...<head> section of template
3) Make sure Google detected code on your page by updating it's status in Analytics interface
4) Then wrap actual call of urchinTracker in Javascript's eval function like this:
<script src='http://www.google-analytics.com/urchin.js' type='text/javascript'>
</script>
<script type='text/javascript'>
eval('_uacct = "your_id_goes_here"; urchinTracker();');
</script>
Click "Save" and it should work! I don't know what actually prevents Google Analytics code from running properly, but wrapping it with eval() call works.
