Anonymous Monk,
What version of AS do you have? Chances are if you have 5.8 (which is required for Hash::Util), you already have it. Try executing:

c:\>perl -MHash::Util -e "print 'ok';"
[download]

If that doesn't cause an error (be sure to specify path to perl.exe if not in PATH), then you are all set. If you do not have AS 5.8, you can upgrade. If you have 5.8 and it failed - you should probably re-install since you have at least one issue. Finally, if you need this functionality for an earlier version or you just want to learn for the sake of learning, you can create your own module by creating a tied hash. See perldoc perltie

Cheers - L~R