#!/usr/bin/env perl
# Confluencer.pl
use HTML::WikiConverter;
my $wc = new HTML::WikiConverter( dialect => 'Confluence' );

my $ecto = do { local $/; <> };
print $wc->html2wiki( $ecto );

Save the code to a file ending in '.pl' and put the file in ~/Library/Application Support/ecto3/scripts/. Restart ecto and you'll find it under the Scripts submenu of the Tools menu.