Creating a free-rhythm line in anotherwise metered score

I have composed a choral Requiem that underscores/supports a verse of Javanese sung poetry (macapat). How can I have the one solo vocal line insribed without any fixed meter, just basically marking the pitches for the conductor, and showing the timing for the Javanese singer, that doesn't require the strict timing of the assumptions of the choral section. The interaction of the two senses of musical time is at the core of the piece. Can I get rid of the bar lines altogether on that line and just use note heads to show (relative) pitch somehow?