The S90 is not yet officially supported by Camera Raw.
Eventually, when it is supported, you can use the latest version of the DNG Converter to process a S90 raw file into a DNG file, which can then be read in CS3 (e.g., using Camera Raw 4.6). This will enable you to perform S90 raw processing in CR 4.6.
Thanks Eric. What is the best way to get updated when the S90 files are supported in Camera Raw? Is the a good group/forum to subscribe to that would notify me?
Yes. There will be an announcement in this forum whenever a dot release comes out.