in reply to
Re^2: Interactive post-coloring of readline input?
in thread Interactive post-coloring of readline input?
Actually, you should spend your time reading the manuals for Readline library. For example here .
Once you understand, which facilities the library provides for interacting with the users input, you should be able to find appropriate front-end functions in Perl. I see there functions like rl_insert_text, rl_delete_text which lead me to belief, that it is possible to do what you want. But personally I've never tried to do it.