C++ typeid()

Does anyone know how typeid() is implemented in C++???
I mean, how do I make a function like typeid() where I can pass the TYPE as a paramter.

Example:
int main()
{
    typeid(int);//<-- works of course
    f(int);//<-- how to do something like this
           //        without using macros or templates
}

Fine then.
Lets say that C++ can't acomplish that
using macros and templates.

In that case, how about overloading typeid?
I'm sure THAT's possible, right?

There is always more than one way to skin a cat.
Its just a matter of creativity