It seems that voxels are starting to become a little more popular among the indie crowd, as I've seen some new activity in the creation of voxel engines and displays.
Lately I've been in contact with one such coder working on a voxel engine. However it's more suited towards a different style of games instead of a FPS. The limitations of sprite sizes will prevent me from being able to use it at its current state. However I proposed to do a future project with it, geared towards a NES style to it, most likely adapting one of my other projects to the style...
There are some new options for progressing this project from it's current slumber. Although I had iffy success getting the basics of Voxlap to work, and Evaldraw being not the ideal for creating a game such as this, I found that ZDoom has recently added a branch off project that supports voxel rendering.
What caught my attention was sample shots that some had of a wall and floor tile from Doom converted into a voxel object. So I may be able to get what I need from it's open source code to figure out my own voxel sprite system.
My other choices are to go back to Voxlap, create my own voxel rendering system or find someone to create a basic voxel drawing chunk that I can incoorperate into my project from the Zdoom voxel project.
When I think about it, I may be stuck with trying to figure my own method of rendering...but time will tell.