You can use sky dome to simulate some very nice cloud movement without any special techniques (animated tga bla bla).
Make a layer with a normal still, clear sky and then put another layer with the clouds and set their speed_u and speed_v to some value.
The only problem is the fog but if you can paint it on the horizon you could make some very impressive skies. Here's a screenshot of what i've done (but there's the problem of bluring which i hope can be resolved using the fog and that horizon:
http://dimenzije.topcities.com/problem.jpgPS: copy paste the link to your browser because it doesn't work otherwise.
