Bert, you are wrong. Port is not needed. One may address a pin without mentioning the port. Neither you need a pointer. All ports are bit addressable.

sbit Led_Pin = P0^0;
...
function(Led_Pin, ...); //function call

But I wonder if Mahmood really needs all this. According to his example, the thing is to activate or turn off a LED. So, why not to write simply :
Led_Pin = 1;
or
Led_Pin = 0;
????