The comment has rightly pointed out to a way that one could programatically set the preferences of SWT Browser widget. The way it could be done is shown in the following code snippet.
Browser browser = MozBrowserUtil.openMozillaBrowser("about:blank");
nsIServiceManager servMgr = Mozilla.getInstance().getServiceManager();
nsIPrefBranch prefs = ( nsIPrefBranch )servMgr.
Again, I thank the anonymous commentor for bringing this to my notice. I appreciate all your comments and would be better if you leave me atleast an email or a URL to your page/blog so that I can get back to you.