The updated ISSM package with support for the Quark SE microcontroller C1000 will be available within the next day or so - if you signed up you should receive a notification once it is available.
The DataSheet is available at Intel® Quark™ SE Microcontroller C1000: Documentation and other supporting collaterals will be made available very shortly.
We will have a Developer Board for the C1000 but it is not due for release until around mid October.
It's available now, "Update 1" - you can download the full install package here:
I have just downloaded this and installed on Windows 10.
When you download through that link it will say at one point that this is "D2000 only" - ignore that; the package is the full ISSM installer supporting both D2000 and C1000