Using Twitter's Bootstrap in Joomla 3

Question

It seems you have to look to: http://docs.joomla.org/Creating_a_custom_form_field_type. You could define a custom field by extending the Jform class:

<?php
// Check to ensure this file is included in Joomla!
defined('_JEXEC') or die('Restricted access');

jimport('joomla.form.formfield');

// The class name must always be the same as the filename (in camel case)
class JFormField<FieldName> extends JFormField {

        //The field class must know its own type through the variable $type.
        protected $type = '<FieldName>';

        public function getLabel() {
                // code that returns HTML that will be shown as the label
        }

        public function getInput() {
                // code that returns HTML that will be shown as the form field
        }
}

With the getInput() function you could return any html.

Or try to use jQuery to style your forms (eample):

<body>
<div class="container">
    <input type="text" name="subject">
</div>  
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>    
<script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/js/bootstrap.min.js"></script> 
<script>
$('input[name$="subject"]').wrap('<div class="input-prepend" />');
$('.input-prepend').prepend('<span class="add-on">my-icon</span>');
</script>
</body>