Is it feasible using .htaccess or any other apache forces to create a custom server value within the php array $_SERVER.

for instance

if($_SERVER['is_special']) {
    echo "Yeah for us!";
} else {
    echo "No you fool!";
}

I recognize I request lots of questions that the reply is no so you can let them know.

Try the [cde] directive:

SetEnv

Rapid response is no, however exactly what are you attempting to accomplish?