"The Perl community" is a collection of many other overlapping communities that all just happen to have perl in common. I'm sure some subset of the Perl community will think your idea has merit, so the way to garner support is through implementation. Write code. Put it on CPAN. If it's useful, people will use it. (Especially if you advertise by giving talks at perl conferences or write tutorials for perl.com, etc.)

If you're looking for something more than just putting it on CPAN, then you'll have to do more for the community. Keeping with your example, show why having Class::Interface::Iterator is beneficial to the perl community. Show how it would typically be used. Show how "broad adoption" is important to the benefits it provides. Show how having it won't hurt (e.g.; make everyone pay a speed penalty for the benefit of just a few). Convince the appropriate perl gurus to agree with you. Et cetera.