I want to extend Struts 2 s:select tag. Can somebody explain step required to do the same. Also if there is any hook or implementation available in Struts2 framework for the same
You can start by examining the freemarker templates (default is freemarker but it can be velocity or some other template engine). See http://mikeski.net/site/node/16.
If that is not enough for you then you could extend or create your own implementation of select tag. http://joshuajava.wordpress.com/2008/12/27/creating-custom-components-with-struts-2/