I've written a Kontakt script which can turn most any instrument into a velocity layer crossfaded one (using equal-power crossfading to avoid volume dips). You also have the option of toggling crossfade mode on and off at any time, just like with Vienna Instruments. Practically all you have to do in order to use the script is to specify the number of velocity layers and the top velocity of each one. It doesn't take more than 30 seconds to setup. The script and usage instructions is available for download from my scripts web page (please note the first setup step).
If you like this script please consider supporting the development. I welcome all feedback!
Note: due to Kontakt not directly excelling in script interoperability it is currently not possible to combine this script with SIPS, but hopefully it will be possible to provide a workaround. If you want NI to improve script interoperability please feel free to voice some support for this feature request.
Acknowledgements: many thanks to R.D.Villwock aka. 'Big Bob' for developing his amazing math library on which this script heavily relies.