Whoops... I didn't mean to delete your first post : / I clicked "edit" instead of "reply" by accident and I didn't realize the mistake until it was too late. Anyway, your question was basically the title of this thread.
You can draw 2D sprites in Voxlap using drawpolyquad(). I originally wrote this function for PINGBALL to speed up the rendering of the table plane. Before drawpolyquad(), I was rendering the table plane as a KV6 sprite : ) The documentation in VOXLIB.TXT isn't very good, so I'll elaborate a little:
The parameters are very similar to the way you draw quads in OpenGL. You specify the 4 vertices in loop order. Vertices are in VXL world coordinates (0-1023,0-1023,0-255). (drawpolyquad() does a rotation and translation inside it). You specify texture coordinates for the first 3 vertices of the quad - my code calculates the 4th one automatically. Texel coordinates range from 0 to the picture dimensions. Textures are clamped - which is good for sprites. You'll need to use some matrix math to calculate the 4 coordinates of the sprite's quad to make it face the direction you want.