Okay; I finally got time to work on this issue. I looked at Die::Alive and Safe::World but this not quit what i want!
I wrote a C++ wrapper around the <edit>Perl-</edit> C-API which has a function to overwrite a internal perl funcion which looks like this:

static const char *CoreGlobal = "CORE::GLOBAL";

bool Interpreter::Overwrite(const char *funcname, const char *newfunc)
{
    if(!gv_stashpv(CoreGlobal, 0))
        return false;

    static size_t len_CoreGlobal = strlen(CoreGlobal);
        
    size_t len = strlen(funcname);
    size_t size = len_CoreGlobal + len + 16;
    char *fullfuncname = new char[size];

    strncpy(fullfuncname, CoreGlobal, size);
    strncat(fullfuncname, "::", size);
    strncat(fullfuncname, funcname, size);

    GV *funcgp = gv_fetchpv(fullfuncname, TRUE, SVt_PVCV);
    GvCV(funcgp) = perl_get_cv(newfunc, TRUE);
    GvIMPORTED_CV_on(funcgp);

    delete [] fullfuncname;

    return true;    
}
[download]

now i can do something like the following

Interpreter perl;

perl.Overwrite("exit", "Foo::bar");
[download]

which would substitute perl's exit with the function bar from the Foo package. (Not ensuring that Foo is already loaded!)
The question is now how to achieve the following:
Everytime the script calls "exit" (or possible die, or similar) my interpreter won't exit but the script stops running.