You are able to turn 'register_globals' on and off via a simple php.ini file.

If you wish to turn it on, create a file called php.ini and within that file add the following line;

register_globals=on

However, should you want to turn it off, you would simply use the following line instead;

register_globals=off

Once you have edited the file, upload to your web content directory that you wish to have the variable set.