Hi Matt, mod_k2user comes with default k2 installation. To do such that you need to modify the file :
/modules/mod_k2_user/tmpl/userblock.php
arround lines 41 you will see this code :
<li>
<a href="<?php echo $profileLink; ?>"><?php echo JText::_('K2_MY_ACCOUNT'); ?></a>
</li>
feel free to modify it into what you want