Well #!/usr/bin/php is just another way to use the PHP Engine it should be the first line called the shebang, the path which must be after it is the path to the program to interpret the script.
Now to the practicality of you actually doing it, well there isnt any. Mainly because there would be so much to update, and get working again. If you really want to have it working I suggest getting a new host or find another forum to use.