Only way to make it would be to have all the statics as bundledmeshes, which casts dynamic shadows.
Fun to code perhaps and to look at on youtube, but not for adding as feature to a BF2 mod.
Why not ? As already suggested, it could be used at some awesome dusk/dawn maps, where you see the sun going down as the battle rages. 50 minutes of round time would be plenty of time to have it even in real time. Just imagine, sun is going down behind a hillside, casting long shadows of the trees. The further it gets down the more it blinds the people assaulting the hillside, and then, when its behind it and darkness rises, only tracers and explosions would light the assault ..
Aaaaah that would be so awesome