You don't need s:checkboxlist
to implement the functionality that you need.
Download the following
http://github.com/ehynds/jquery-ui-multiselect-widget/raw/1.13/src/jquery.multiselect.min.js
http://github.com/ehynds/jquery-ui-multiselect-widget/raw/1.13/jquery.multiselect.css
and add them to your jsp. Then use a s:select
element with multiple
attribute set to true
<s:select id='your_id' multiple="true" name='your_name' key='key_from_properties_file' theme="xhtml" list='your_list' listKey='your_id' listValue='your_value' />