In your index.php (or wherever you call the miniposts plugin), there should be a line that says get_mini_posts() which will call the basic function using the defaults
Earlier in the page, he says get_mini_posts(format, permalink_text, zero_comments, one_comment, more_comments, limit) is the structure for the function, so to use the defaults mostly, but change the limit, you'd pretend to fill in the defaults -- but with nothing there.
So, try get_mini_posts(,,,,, 2) (it works best to copy the whole function, and delete the bits you don't want).
Hope this helps!