There is still some work to do on the texture blending, I only have it working for some of the terrain shaders at the moment. Also there are still some issues with colour tinting, eg the golf course should be tinted terrain, and parts of the beach have some different masking, but I haven't figured out the algorithms yet. If you know of any details that might help, would be great to hear it!
I added a tool to disassemble the shaders, but I find it quite time-consuming to read the shader assembly code...
On second thought, I think the 2nd vertex color channel is working fine, it's probably just some decals missing that puts me off.
Speaking of vertex colors, I have a request: Would it be possible to add an option to instead of showing textures, to just show vertex colors? Both for the 1st and 2nd channel, separately? I noticed you can see the vertex colors just before loading the textures. I realize this sounds like a useless feature to you\ most people, but it's useful for me.
As for '_tnt' shaders, I believe it works fairly simply: You feed it with a lookup sampler, typically recognized by the '_pal' suffix and appears to be always 256x4 pixels. In the shader you have a parameter called 'TintPaletteSelector' which contains an 'X' and 'Y' value, which selects the color from said texture sampler and then multiplies(?) it by the diffuse color.
Wouldn't know about the beach masking, i'll look at it one of thse days.