I would love to at least be using Perl 5.8 at this point, but I'm subject to two limitations which I cannot control directly (and may only influence indirectly):

1. the Perl version which is standard in the environment where I do my official development work
2. the Perl versions which are standard in the customer environments where my module may be deployed

That's why I'm currently at 5.6.1 - but I don't think my problems are related to my Perl distribution. In fact, you may have addressed my confusion in your first comment (use lib). I'll post another reply when I've had a chance to run some tests.