You cant override die or exit since they are language constructs, not member functions of a parent class.
Still, how is it that you do not have full control over your project's files? Can you not collaborate with other contributors to make the change?
If you have access to PHP itself, you might be able to modify and re-compile PHP so that die and exit work the way you want, but that's really bad form, if you have the skills to do it.