http://sumarsam.web.wesleyan.edu/Intro.gamelan.pdf has some good notation examples. keep in mind though that the notation only provides the 'skeleton' of the form. depending on the instrument and the context, musicians will elaborate and ornament the basic melody. 'proper' elaboration is something learned by doing, it cannot be read from a book. the javanese only really use this notation for documentation, for the most part forms are learned by memory. part of why you couldn't use western notation for javanese music is that there is no standardization of pitch. one gamelan's slendro (pentatonic scale) may be completely different than another gamelan's slendro, not only in the frequency of the tonic but in the relative position of all pitches.