I am quite new to sitemaps, but I understand that in a news sitemap you are able to specify keywords under the <keywords> tag. I'd like to know if there is a way of automating this keywords tag, to apply related keywords to a specific article / news story?
You could try entering the text into an array and see what frequency certain keywords/phrases are used and use them however you would need to eliminate noise words such as "the" and "and". The words used the most could then be used as the keywords.
Could anybody suggest me how could I include news sitemap of my blog to webmaster tool as when I try to submit it through my webmasters account, there is not any option of news sitemap...
That is true it requires a bit of programming , you can use a programing languange with your .htaccess then everythinh will have a keywords, but i need to know the type of script and blog script you are using?