try this
i take it you already saved the yahoo archive?
go to veiw archive to show the date and time and who you chatted with,expand the borders to as far as they will go to show the most dates you have chatted,maximize the screen.
you may have many months saved on the archive,so start at the first date and print that page,then roll the screen to show the next page of dates until you have printed them all and turn the pages over and print on the other side
then press print screen or ALT+ print screen.
open paint,left click then paste.
goto file,then page setup.
click landscape,then fit to 1 page by 1 page.
now print
and preview page
simples
theres no need to show them what your conversation is about?
you maybe having a sexy chat?