royce@heffalump$ perl -e 'use Term::ReadKey;'
royce@heffalump$ perl -e 'use Term::ReadLine;'
... and making sure that vi key bindings were listed in my .inputrc:
royce@heffalump$ grep editing-mode ~/.inputrc
set editing-mode vi
... I still couldn't use 'em, as demonstrated by what happened when I tried to use movement keys:
In my research, I discovered that Ubuntu folks were installing a different ReadLine. I eventually found the devel/p5-ReadLine-Perl port, which has this pkg-descr:
Perl 5 ships with a module called Term::ReadLine which is an interface
to command line editing and recall. The version that ships with Perl
is only a stub, and offers little functionality.
This module supplants the Term::ReadLine stubs with real command line
editing and recall facilities, written entirely in Perl. Applications
that use Term::ReadLine do not need to be modified to gain the benefits
of this package; it will happen transparently upon installation.
After installing p5-ReadLine-Perl, I'm up and running.