Learn what is, and how to use Codeigniter Drivers.
I am sorry for my English ... It’s poor but I am still learning it.
Can you perhaps figure this out? How to do this right?
Well ... It seems, you did it right :D
You added new driver, and then (or before) modified valid drivers.
I dig into drivers and I found no other way how to extend them (maybe I didn’t dig enought :D).
It can be done. I just put my new drivers in the /application/library/Cache/drivers and copied the CI version of Cache.php to /application/library/Cache/
Then I can add the names of my drivers to my version of Cache.php
Now it works without modifying the CI files. Can still use the CI-drivers too.
I have found this tutorial