How should I handle classes and files on which a Library depends?

[eluser]kirkryyn[/eluser]
I'm considering writing CI Library wrappers for some non-CI specific libraries. However, I do not know where I should place the dependencies. In Cake, there was a concept of a Vendors directory where outside code could be placed. Is there something for CodeIgniter that I simply missed?

For instance, say I want to create a CI Library to wrap some AWS S3 software that is implemented as several class files. Where should I place those class files and how should I require them from within my CI Library in such a way that it would be easy for the person using the Library to install everything in their system?