I found mt-rebuild which allows you to schedule a rebuild of an entry/page/index which is just what I needed to force a rebuild of my main index page on absocachinlutely to include my latest finds in the side bar of the page. I had to rename my Main Index to MainIndex and then include the blog id, set the mode to index and provide the template name in a cronjob as follows:-
/full-pathname-to/mt-rebuild.pl -blog_id=9 -template=MainIndex -mode=index
You didn't have to rename your template. Placing it in quotes would have done the trick.
/full-pathname-to/mt-rebuild.pl -blog_id=9 -template="Main Index" -mode="index"