I use two XSL files - one to document the WSDL for the operations, one to document the XSD for the data being passed around.
Unfortunately, so far, I haven't found a single cohesive solution, so I work with two XSLT files which transform the WSDL and the XSD respectively into HTML documentation.
WSDL Viewer does the job for the WSDL and produces a first HTML document, and xs3p does the same for the data contain in the XSD file.
