The only way I can think to do that would be to use a custom front page layout – but then you would lose the default infinite scroll blog posts on the homepage. You could still have the blog posts display on a different page, but I imagine that’s not what you want.
Alternatively you could create blog posts as testimonials and add them to a testimonials category. If you gave them the blockquote post format they would stand out on the homepage.
It wouldn’t be quite the same as using the testimonials feature but might do what you want.