Enlarge a sheet of music paper -- or draw your own -- so that it is big enough for your kindergartner to be able to put the characters you are going to draw on it.
Tell your chil, to keep things simple, that the treble clef means that you play with your right hand and the bass clef means you play with your left hand. Make music flash cards of the treble and bass clef and when you hold them up, ask your kindergartner if it is right or left hand that plays when he sees the sign.
Explain to your kindergartner that each octave has eight notes and they simply repeat over and over. Turn it into a rhyme and keep practicing until your child can go through C,D,E,F,G,A,B,C by rote.
Draw characters for each whole note using a word your kindergartner knows. C, for example, is a carrot, D is a dog, E is an elephant and so on. Have your kindergartner color the notes and make multiple copies.
Teach your child that each note has a "home." And that middle C starts just outside the lines on the music paper. Show him where it is on the keyboard and attach a character to the music and a duplicate to the keyboard.
Work through the lines and spaces until your kindergartner knows where each note fits on the music sheet and can coordinate it with the right key on the keyboard. You can also tell her that "FACE" is for the notes in spaces and that "every good boy deserves food" is for the notes on the lines.
Draw poster-size music sheets and enlarge the note-characters. Put the notes up on the sheet and ask your kindergartner if she can play the song on the keyboard.
Review notes and clefs frequently. Once your kindergartner is comfortable with the basic concepts you can introduce half-notes and quarter-notes, still keeping it as a fun exercise rather than "work."