CompuServe Messages

I'm working on a network check-out utility for AutoCAD and need to be able to extract XREF filenames from a drawing file. The check-out utility will actually fetch and keep track of the files that AutoCAD needs from the drawing, making the necessary network requests and placing them on the local drive before AutoCAD loads. It has to run outside the AutoCAD environment (obviously). I know bupkis about AutoCAD (also obviously); I'm a systems and network programmer under contract with a software vendor.