Add some CSS and JS at the question text using the source code mode of the editor. Here is some sample code:
<script type="text/javascript">
$(document).ready(function(){
$('#answer{self.sgqa}').select2();
})
</script>

<style media="all" type="text/css">#question{QID}
{
overflow: visible !important;
}
#question{QID} .select2-container
{
height: 200px;
}

#question{QID} .select2-container
{
width: 400px !important;
}
</style>

Activate the survey, add a response and view the responses.