Mac users interested in Zeropsx ver 2.5 generally download:
zeroPSX Hybrid is a heavily modified and upgraded version over the old zeroPSX Playstation Emulator.
zeroPSX Hybrid is a custom Wrapper for ePSXe.
This approach is also taken in PCSX, PCSX2, and Project64.
Requirements: any Intel mac, X11 and the CXZ Jade Engine.