The dx7 level Envcube effect(like above)isn't correct,because real cube reflection only depends on the view-position,dosen't depends on look-at position.In other words, it needs cube-space(or world space)reflect vector,not the camera-space reflect vector.
You can calculate the tex-coordinate(the correct reflect vector) through vertex shader.But if you want to make a per-pixel env-cube or bump env cube effect,you should use both vertex and pixel shader,calculate the reflect vector in pixel shader.I wrote such a effect,It work fine in my D3D-8.1-API App ,but it seems not friendly with GS6.22,thus it makes a totally wrong result