Hey, just a thought -- you have a SQL db -- do you have SSIS installed? If so, you could use SSIS to copy data to a SQL table from your PeopleSoft db, couldn't you? And schedule it to run as often as needed to update your SQL table.... That way you wouldn't have to build a web service for your PeopleSoft database.
However, if that won't work for you, here's a web service tutorial that might help you get started...