I hope it's ok for resurrecting this thread.
An ex-developer of Argonaut has recently uploaded online various Alien Resurrection ps1 prototypes and alphas including the prototype featured on the screens on the unseen64 page
AVP-CAPCOM posted a link to. The prototype from the E3 demo is also uploaded.
I'm not sure if I'm allowed to post links to the files as you need an emulator to play them. Thought I'd mention them in case anyone was interested in playing them at all. I'm currently playing A:R on original hardware and while discussing the game someone told me about these prototypes. I've only tested one so far dated 11/08/99