Hi Ankit,
The message boards that come out of the box is it's own portlet. It is possible to embed portlets in portlets in Liferay, but if the out of the box portlet is not going to meet your needs, then I am not sure that is going to get you any closer.
I think what you are asking is how you can leverage the message board backend (services) that Liferay provides out of the box, but build out your own front end ... is that it? if so, which version of the portal are you using?
