Click here to download a "test toolbox" developed by FOSSEE to get started. A "test toolbox" is a scilab toolbox made by FOSSEE that has example code to get started in the toolbox creation process.
Click here to download the external-library. It will be required to successfully build the test_toolbox. See the document below for instructions.
Click here to download a PDF document that describes how to build your own toolbox using the "test toolbox" developed by FOSSEE.
Click here for a Spoken Tutorial that teaches "Developing Scilab Toolbox for calling external C libraries".