I am actually at the same position when I first wrote godrays for Morrowind. I was able to get the effect without depth buffer. But it was full of artifacts, it was ugly and it was static, just like this version. Without depth buffer access, I can't fix those issues. To make it dynamic, I will need variables like sunvec and eyevec or sunpos. I don't know if they are available.
Until depth buffer feature, that's all folks. :shrug:
Well, I would probably try to trick Scanti transfer back to MGE. There are some incomplete shaders of him, IIRC.
I've read threads 11, 12, 13. We were at the same position back then for MGE, everybody was excited about depthbuffer access and its possibilities, but nobody could find it. Then 2 months ago one guy came and fixed it. Just like that. The problem was discontinued developments and the project hugeness. It turned out depth buffer was always there.

With some patience, like 8 years, you might get it too.

I'm actually working on rewriting OBGE at the moment. Having access to the depthbuffer is theoretically possible. It's not just a case of finding where the depth buffer is. The normal depth buffer in dx9 isn't accessible. Fortunately ati and nvidia have there own proprietary readable depth buffer formats. What you need to do is find out what card the user has. Create a readable depth buffer for that card type and switch it with the depth buffer that the game creates. It's fiddly but possible.
When I do the rewrite I can get the sun vector for you. I'm not sure about the sun position, I haven't looked for that yet. I think the game uses parallel projection as far as the sun rays are concerned. (I suppose the sun is so far away that any light rays are as near to parallel as makes no difference). I think I know where the eye vector is but if I remember correctly it suffered from jitter. (Even when your character was still the vector moved around slightly).
Scanti released that memory dumper. Am I right in thinking that could be used to find the depth buffer? And what is it that we would be looking for in the dumped memory that would signal the location of the buffer? If anyone knows, a whole bunch of people looking for the memory address would be faster than just one person, and I for one would help look for it.
The memory dumper would only help if you knew what you were looking for and even then most of the depth buffer is stored in the graphics card's memory. I have a pretty good idea where it is but as I said above it's not that easy.