Thank you for inviting me to answer for this question but I tend to stay away from php and its frameworks. However that said yesterday I briefly looked at something in PHP and found it almost readable, and very similar to using the Django Python Framework.
I would highly recommend looking at the documentation, its probably something easy but just working it all out. If you didn't want to use Disqus, would immagine to try building your own commenting system to work, would save money in the long run than using another api or addon I suspect that you might need to pay for :)