$(function() {

  // these default equivalents were obtained from a table of equivalents
  // provided by sugar.js sorting alogrithms: http://sugarjs.com/sorting
  /*
  $.tablesorter.characterEquivalents = {
    "a" : "\u00e1\u00e0\u00e2\u00e3\u00e4", // áàâãä
    "A" : "\u00c1\u00c0\u00c2\u00c3\u00c4", // ÁÀÂÃÄ
    "c" : "\u00e7", // ç
    "C" : "\u00c7", // Ç
    "e" : "\u00e9\u00e8\u00ea\u00eb", // éèêë
    "E" : "\u00c9\u00c8\u00ca\u00cb", // ÉÈÊË
    "i" : "\u00ed\u00ec\u0130\u00ee\u00ef", // íìIîï
    "I" : "\u00cd\u00cc\u0130\u00ce\u00cf", // ÍÌIÎÏ
    "o" : "\u00f3\u00f2\u00f4\u00f5\u00f6", // óòôõö
    "O" : "\u00d3\u00d2\u00d4\u00d5\u00d6", // ÓÒÔÕÖ
    "S" : "\u00df", // ß
    "u" : "\u00fa\u00f9\u00fb\u00fc", // úùûü
    "U" : "\u00da\u00d9\u00db\u00dc" // ÚÙÛÜ
  };
  */
  // modify the above defaults as follows
  $.extend( $.tablesorter.characterEquivalents, {
    "ae" : "\u00e6", // expanding characters æ Æ
    "AE" : "\u00c6",
    "oe" : "\u00f6\u0153", // œ Œ
    "OE" : "\u00d6\u0152",
    "d"  : "\u00f0",  // Eth (ð Ð)
    "D"  : "\u00d0",
    "o"  : "\u00f3\u00f2\u00f4\u00f5", // remove ö because it's in the oe now
    "O"  : "\u00d3\u00d2\u00d4\u00d5"  // remove Ö because it's in the OE now
  });

  $("table").tablesorter({
    theme : 'blue',
    // Enable use of the characterEquivalents reference
    sortLocaleCompare : true,
    // if false, upper case sorts BEFORE lower case
    ignoreCase : true
  });
});

<table class="tablesorter">
  <thead>
    <tr>
      <th>Account #</th>
      <th>First Name</th>
      <th>Last Name</th>
      <th>Age</th>
      <th>Location</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>a1a10</td>
      <td>AnderE</td>
      <td>Parker</td>
      <td>28</td>
      <td>Béchar</td>
    </tr>
    <tr>
      <td>a1a2</td>
      <td>Ändere</td>
      <td>Hood</td>
      <td>33</td>
      <td>Bebington</td>
    </tr>
    <tr>
      <td>A1a1</td>
      <td>Andére</td>
      <td>Kent</td>
      <td>18</td>
      <td>Berlin</td>
    </tr>
    <tr>
      <td>A2b2</td>
      <td>CotÉ</td>
      <td>Almighty</td>
      <td>45</td>
      <td>Beckum</td>
    </tr>
    <tr>
      <td>A1d2</td>
      <td>CÔte</td>
      <td>Evans</td>
      <td>56</td>
      <td>Curaçao</td>
    </tr>
    <tr>
      <td>a2b11</td>
      <td>CÔtÉ</td>
      <td>Clark</td>
      <td>44</td>
      <td>Béjaïa</td>
    </tr>
    <tr>
      <td>A2b1</td>
      <td>Çote</td>
      <td>Presley</td>
      <td>24</td>
      <td>Bekkevoort</td>
    </tr>
    <tr>
      <td>A1b0</td>
      <td>Andéré</td>
      <td>Carter</td>
      <td>40</td>
      <td>Bègles</td>
    </tr>
  </tbody>
</table>