No word on it being just the first game, or all 3 games. 4th game (don't love it or hate it) had most music arranged by Stewart but composed by 2 other people.
Source is Stewart's official FB account. No word on a disk release. For anyone who wants the music right now, there are ways to extract music files from PS1 games in WAV format. It is originally compressed, but not by much. The WAV files can then be edited slightly if the bass is too much, or fade-out does not work.