share_text="Свой текст "

<script type="text/javascript" src="//yandex.st/share/share.js" charset="utf-8"></script>

<div class="yashare-auto-init"  share_text="В Я.ру"data-yashareType="button" data-yashareQuickServices="yaru,vkontakte,facebook,twitter,odnoklassniki,moimir,lj,friendfeed,blogger,digg,evernote,delicious,gbuzz,greader,juick,linkedin,moikrug,myspace,yazakladki"></div> 

<a counter="no" type="button" size="small" share_text="Свой текст" name="ya-share"> </a><script charset="utf-8" type="text/javascript">if (window.Ya && window.Ya.Share) {Ya.Share.update();} else {(function(){if(!window.Ya) { window.Ya = {} };Ya.STATIC_BASE = 'http:\/\/img\-css.friends.yandex.net.cstatic\-kiev01.corba.yandex.net\/';Ya.START_BASE = 'http:\/\/my.ya.ru\/';var shareScript = document.createElement("script");shareScript.type = "text/javascript";shareScript.async = "true";shareScript.charset = "utf-8";shareScript.src = Ya.STATIC_BASE + "/js/api/Share.js";(document.getElementsByTagName("head")[0] || document.body).appendChild(shareScript);})();}</script>

Думаю было бы лучшее добавит свой тест вместо Кнопке Поделится