I recently purchased a K70 RGB and wanted to configure the CAPS NUM and Scroll lock keys to light up a different color indicating their toggled state. After many attempts with the iCUE software I gave up and decided to write my own utility.
The main issue I was encountering was any iCUE config I came up with would get "out of sync" when the workstation was locked, and I routinely lock my PC.
It's a C++ MFC application using the Corsair SDK. I've published the source and x86/x64 setups to Git. I've tested on Windows 10 x64 without issues. That said I whipped it up in a day or 2 so use at your own risk.
It's only been tested with the K70 RGB but I imagine it should work with most Corsair keyboards.
https://github.com/mikerossman/ToggleColors/releases