I have managed to redirect users for registration, and passwords through the pluggins with simple redirects..

if(isset($_GET['action']) && $_GET['action'] == "registernew") {
header("Location: http://url.com/register.php");
}

if(isset($_GET['action']) && $_GET['action'] == "sendpass") {
header("Location: http://url.com/forgotpass.php");
}


however I also need the logout to redirect, the following is ignored..

if(isset($_GET['mode']) && $_GET['mode'] == "logout") {
header("Location: http://url.com/process.php");
}

Is it possible to achieve the redirection without changing the core of the functions which I have located and could do but would prefer not to.

Logout is executing faster than any of the plugins inclusion, so most likely you may try to paste your code under setup_options.php, or bb_specials.php.