Hi Viththal,
From my perspective, using the custom attributes tag here feels a bit like shoving a square peg into a round hole. I think I would opt for a JSP hook that uses the CountryLocalService to get the values you need and then in a JSTL foreach loop add your <aui:option/> values inside an <aui:select/>.
Alternatively, I suppose you could define your own taglib, but if you did that I would probably try to do something more generic where yo ucan pass in a Map with the data the you want bound to the list. In fact, I'll bet such a taglib already exists out there that you can use. The quickest solution though I think would be the one I outlines above.
