If you use the plugin: Featured Content Gallery you should be able to feature as many posts as you want.
I have the same problem. My blog is in a sub-directory, http://raymondtreasureproperties.com/blog and according to the Google Sitemap XML Generator plugin, my sitemap should be: http://raymondtreasureproperties.com/blog/sitemap.xml But when I enter it, nothing shows. When I submit to Google Webmaster it shows an error getting the sitemap.
I have been searching all over the web for a solution to this problem but can’t find an answer.
Please help!