I hate to be the bearer of bad news, but it looks like the s200 is completely unsupported
Unfortunately, due to Linux's "marginal OS" image or a desire to keep "trade secrets", some manufacturers refuse to provide drivers or to detail their interfaces so that others can write them. Also, in the open source development model, the age and popularity of a given device can also affect whether, how quickly, and how well a driver gets written for it. So Linux users have to be particularly careful about what hardware they buy for their systems. Things are gradually getting better, but consumer peripherals like scanners and printers are still among the riskier areas.
With the information from the sane page above it shouldn't be hard to track down a scanner that does work though. You could probably pick something up cheaply on ebay or the like, for example.