Read More tag to read less?

Hi,
I installed a plug “read-more-right-here” and have further customized the main index template so that the more tag says what I want. The only thing I cannot figure out how to do (I can’t even figure out how to google it!) is that, once the Read More link is clicked, I would like the link to jump to the end of the post and say “Read Less”. Right now, you can click on it once the post is expanded and it will ‘roll up’. But you have to go back up to where the link is… I would like the Read More link to, essentially, disappear and reappear at the bottom, saying Read Less! Is this too much to ask? I have seen this on a number of sites (not wordpress) so I’m guessing it is something simple…

Thanks in advance,
Debbie