Joe... I do not know what kb you are using, whether it has a hard drive or not, but I can give you some general info about midi files ...
You can do a GOOGLE search for Elvis Presley + midi files ...
Go to one of the sites shown, and pick a song ... Right click on the song and "Save As..." - I usually save mine to a floppy disc (I use a kn6000)
Play the midi file through your kb ... Some will be good, others will not ...
depending on the kb you should be able to change instuments (voices), volumes, panning, etc.
Eliminate or lower the volume of the lead instrument... you don't want this playing while you are singing ... if you absolutely need the lead, change it to something like strings, or 'vocal oohs', and keep the volume low ...
Some other members may have some additional tips for you.
If I could get an e-mail to you I have a number of links to sites for midi files and lyrics and chords ... As I stated, I also have a number of 'lead sheets' with the lyrics, chords, and melody line...
t.