COREPATH not used for core-classes

[eluser]PhilTem[/eluser]
Ah, sorry. Got your question wrong.

Hm, I think the easiest is using symlinks. That means, you have one location for your extended core-files and in every application you want to use them you just symlink the files. This way CI will kinda like "think" the files are there where they should be though they will be in one common location.
If you're on a windows machine you will simply create links but now symbolic links.