4th Mix should work exactly the same. If it helps at all, here are my working settings for the Pete's OpenGL plugin:
Plugin: Pete's OpenGL Driver 1.1.54
Author: Pete Bernert
Card vendor: Matrox Graphics Inc.
GFX card: Matrox G400
Resolution/Color:
- 640x480 Window mode
- Keep psx aspect ratio: off
Textures:
- R8G8A8A8
- Filtering: 3
- Caching: 2
Framerate:
- FPS limitation: off
- Frame skipping: off
- FPS limit: 60
Compatibility:
- Offscreen drawing: 3
- Framebuffer texture: 0
- Alpha multipass: on
- Mask bit: on
- Advanced blending: on
Misc:
- Scanlines: off
- Line mode: off
- Unfiltered FB: on
- Dithering: on
- Full vram: off
- Game fixes: on [000002e0]