If you can install Strawberry Perl to a directory of your choice, all you need to do is specify the Perl you want when you start your script. Instead of
Set your PATH and the .pl association to the version you want to use by default. You could even create different associations for different versions. For example, .pl512 could be associated with an installation of Perl 5.12.
You can also change the PATH within a console and it will only affect what you do in that console.