Yes, it's an old mirror script.
I made a vertical mirror effect using C-script a while ago(JuOn?). But it's gone along with my old HDD .
B2T, to create a mirror effect in C Script, there are some 'rules':
1. The mirror surface must be flagged mirror(of course). And the other surface of the block should be flagged none.
2. The block should be the outer area(doh, how should I describe this). There must not any block or model behind/intersecting the block
3. Creating vertical mirror is a bit tricky since each mirror direction needs different code, which I forgot, sorry :D, but the point is, rather than changing the view_mirror.z, you change, view_mirror.x or view_mirror.y(depends on which direction the mirror is facing). The same applies to view_mirror.pan, tilt and roll