I made 2 custom images and also separate the instrument from the FX in Registry, as:
Native Kontrol Standard Instrument Preset, and Native Kontrol Standard FX Preset.
The registry values needs the 2 icons to be at:
C:\Users\Public\Documents\NI Resources
but you can modify them easily to whatever folder you like.
Zip archive includes 2 Windows .ico files and 1 .reg (Registration entry) file.
Mac version, by Diam