Okay, here another small update : I got the CubeMap sample running flawlessly too now!
The thing is, I was comparing my output to that of the never-published Cxbx version of kingofc and saw that Dxbx was showing a black teapot instead of the reflection of the environment.
I couldn’t put this to rest, and after some trial and error I found out that SetRenderTarget failed due to the fact that our CreateCubeTexture patch forgot to pass on the ‘Usage’ flag, which was set to D3DUSAGE_RENDERTARGET in this case. Without this flag (and the right D3DPool), SetRenderTarget indeed can’t render to the (cube)texture; Once I discovered that, the fix was easy enough. (Perhaps the same problem exists in other places too, so this could lead to some other fixes too.)
Here a screenshot that nicely shows how the enviroment is reflected into the teapot now. Cheers!