hi Jedi
i'm glad to help. i've learned alot on this forum, lurking in the shadows ... lol. it took me like 9 months to do 20 postings
the program harmony assistant is a sequencer, music score writer a midi and karaoke player etc. i dont use it sorry cant tell you how it works but theres a tutorial and great explanation on this page:
http://www.myriad-online.com/harmonydesc.htm it allows you to put lyrics in a midi file and save it to disk then play it on your Yamaha keyboard
but you may want to search for the songs you want first cause its probably available on a web site or a newsgroup. i have over 20K midi-karaoke files. in my profile there my webpage and from there you can find many karaoke ressources.
good luck