Hi,
the sdk available from the download section contains the reference manual and source code of the generators, and the drivers.
You'll also find the ref manuals for the core libs
However, as you noticed, you don't have the source code for those.
Additionally, all the source code provided comes with a statement that says it's only licenced to you.
If you take advantage of the drivers/generator api to short cut the licenced designer, then you should be aware that you can't commercialize the resulting package as is without Frans' permission. On the other hand, I don't think there's a problem commercializing it as a service you host.
You just can't redistribute the drivers/generator dll, and even less the core licenced dlls, yet the runtime libs are ok for inclusion in a commercial product.
Cheers