Just rendering it with Scanline should give the same effect as the earlier post, so long as you have a single overhead 'Sun' light (distant) which will illuminate the tops of the waves due to the water material's high specular value. Basically the wave texture is loaded in the Bump channel and the reverse (negative) version is loaded in the transparency channel. This makes the 'troughs' more transparent than the 'peaks', so the under-lying 'deep water' object/material is more visible there.
I posted the .an8 file in the original post, were you not able to load it? It was created and saved in V1.00 though it should work in any version back to probably .97 as it doesn't use anything new.
Also, under View>Preferences, make sure all available checkboxes in the 'File output' section are checked (Textures, Shadows and Transparency in particular).
Re OpenGL vs Scanline, yes, there's a huge difference. Though I don't often use it, I believe OpenGL rendering is roughly equivalent to what you see on screen, whereas Scanline is far more accurate. For reflective, refractive and ambient occlusion properties the ART renderer should be used, noting that it does not respect shadow density settings as Scanline does (if engaged, shadows are 100%).
