As stated in my comment, doing this with `=importXML` and XPath seems tricky.

But doing it programmatically, using the [XmlService](https://developers.google.com/apps-script/reference/xml-service/xml-service) of [Google Apps Script](https://developers.google.com/apps-script/), looks easier.

I have written the following:

    function parseTvRageXml(url) {
       var result = [];
       var xml = UrlFetchApp.fetch(url).getContentText();
       var document = XmlService.parse(xml);
       var root = document.getRootElement();
     
       var show = document.getRootElement();
       var episodeList = show.getChild("Episodelist");
       var seasons = episodeList.getChildren("Season");
       for (var i = 0; i < seasons.length; i++) {
         var season = seasons[i];
         var seasonNum = season.getAttribute("no").getValue();
         var episodes = season.getChildren("episode");
         for (var j = 0; j < episodes.length; j++) {
           var episode = episodes[j];
           var resultRow = [];
           resultRow.push(seasonNum);
           resultRow.push(episode.getChild("epnum").getText());
           resultRow.push(episode.getChild("seasonnum").getText());
           resultRow.push(episode.getChild("airdate").getText());
           resultRow.push(episode.getChild("link").getText());
           resultRow.push(episode.getChild("title").getText());
           result.push(resultRow);                
         }
       }
      return result;
     }

In effect, it fetches the content from the given URL, parses it as XML, and iterates through the elements, extracting values of the elements you wanted, which is stored in a 2-dimensional array (`result`), and returned.

To use this, you must install the script in your spreadsheet. Click the _Tools_ menu &rarr; _Script editor_, and paste the code listed above. Save the script.

In the cell where you want the output, enter 
   
    =parseTvRageXml("http://services.tvrage.com/feeds/episode_list.php?sid=3183")

The result should be a list of episodes, with the following columns:

    Season number | epnum | seasonnum | airdate | link | title

I have set up [an example spreadsheet](https://docs.google.com/spreadsheets/d/1qFryUlGfGT8dp_lx9sSE_7suCV0t8cAg9btM1AOPnSI/edit?usp=sharing) to demonstrate this, feel free to copy it.