CodeIgniter PayPal Checkout Express integration

[eluser]Unknown[/eluser]
I've been searching for PayPal Checkout Express integration for days.

I couldn't find a good document that support this process.

Most of people recommend this website, but the file doesn't exist.
https://github.com/EllisLab/CodeIgniter/wiki/PayPal-Lib

I already tried PHP version code that PayPal provided, but you know it takes time to convert the codes into Codeigniter MVC platform.

So, can you please tell me where I can get a good tutorial?

Thank you.