Contributor - XML module
Provides XML features from Scilab and his language could be an asset to read and write files.
Since Scilab already has a dependency on libxml2 for his internal use, this library seems to be the best one for this feature.
A good start could be to provide the Xpath feature in Scilab and adding more and more XML features later.
You can also have a look at a xml toolbox available on matlabcental for the xml_toolbox. You will only find p-code in this archive, but it gives a good idea of a nice API. Another xml toolbox can be found here. In this archive, all the code can be found. One nice thing about this toolbox: it's GPL !