Rejoice all, I found Yamaoka's secret(?) stash:
http://www.konamistyle.jp/sp/akirayamaoka/more/who.html
Mostly trial MP3s of known songs, but there is an early/alternate "Theme of Laura"! Not the E3 version, but still a nice oddity.
Other nifty tracks are ~1993 demo songs and sparkster midis.
To DL them open the m3u file from the site, which has links like this (won't work anymore):
http://www.konamistyle.jp/customfact...ill2_first.mp3
and replace "customfactory" with "sp":
http://www.konamistyle.jp/sp/akiraya...ill2_first.mp3