You can do this by setting a float : right property on the content div, and using a media query to reset it to left in larger screen sizes. Here's a fiddle.
html
<div class ='container'>
<div class ='row'>
<div class ='col-md-3 col-xs-4'></div>
<div class = 'col-md-6 col-xs-8 floater'></div>
<div class ='col-md-3 col-xs-4'></div>
</div>
</div>
css
.floater {
float: right;
}
/* Medium devices (desktops, 992px and up) */
@media (min-width: 992px) {
.floater {
float: left;
}