I discussed this before (this is a Linux setup) and looking at the functions mentioned in the toolbox there are the following: Maxima, overload-1.3.3.tar, and scilab-scimax-2.1.3.tar. I have found a windows Maxima windows, a SciMax toolbox, and a Overload toolbox. Looking the above link and these 3 items it looks like if I install Maxima (done), and install the last 2 toolboxes I might be able to accomplish this task of using syms in the examples using this code. Will this work?
These are the links to the overload and scimax toolboxes that I found.
Looking at the toolbox and Scilab versions, it looks to be using an old Scilab version. Theoretically, it should work if you're using an old version of Scilab. But I would not be too hopeful. Once again, please contact the toolbox authors directly. You can find them on the ATOMS page or on the Forge page.