Help to apply onion architecture in codeIgniter

I am coming from Java. I want just to apply the technique that shows the pdf Clean architecture. In page 97 implement that technique in the Zend framework. But I cannot do the same things in CodeIgniter. I prefer to stay Independence from framework because I want to concentrate in the business logic. I cannot find any tutorial in clean architecture for Codeigniter. I found only for symphony. Also Codeigniter don't support Depedency Injection(I think!).