Sure, drivers CAN be made from scratch. But without knowing the intricate workings of the hardware-component you're making a driver for, it's really hard and time-consuming. The best that can be done in a short time is a general driver, whereas what you really want is a specific, and thus optimized, one. It's easy for NVIDIA because it knows the workings of its own hardware(
I know the waiting is a pain, but it really will be quicker to get the drivers from the update, or some other "official" source(picking drivers here and there from devices that already have ICS and use at least one identical component). The bonus being these drivers having undergone at least some testing, too.
In short: Reverse-engineering drivers is a pain, and very time-consuming. Chances are we'll have ICS before any really good "home-brew" drivers can be made.