This can be definitely be done with KARMA using a custom Note Map Table although I'm not sure at the moment which GE to choose ... maybe the Pad Holder or RT Bend GE with the pitch bending turned off -- would have to investigate that. You need a GE that will hold the (harmonised) note for the duration you have they root note key pressed and follow exactly what you're playing without any delay.
In any case, once you find an appropriate GE, you can program the Note Map on the KARMA > Name/Note Map tab so that when you play a D the GE will instead play a F#, and when you play an E the GE plays a G and so on. Repeat this for each note you want to harmonise.
You need to turn on the Note Map for the GE on the KARMA > Control tab. Select "Custom" and the "On-All" settings for the module.
You should also turn on the Thru In Zone for the timbre/GE on the KARMA > GE Setup/Key Zones tab to get the harmony you want, in other words, you get both the D and F# sounding at the same time when only pressing the D key. The upside here is that you don't need to use two timbres, you can use one timbre and KARMA does the work for you.
You'll need to consider what to do with the additional notes outside of the scale. There's the "remove" option in the note map's "out" setting, which may be useful here.
For general info on KARMA Note Maps, check out:
http://karma-lab.wikidot.com/karma2:cha ... ated-by-ka
In the Kronos's Parameter guide, Note Maps are explained on pages 132 & 133, and also on pages 114 & 115.
I know this probably won't make any sense if you don't have a basic understanding of KARMA. Sorry...
By the way, I can understand that playing the harmony in the key of D might be a bit tricky for fast passages. What you could do is play it in the key of C and transpose the timbre by +2 so that it sounds in the key of D. It's a lot easier to play these harmonies on the white keys only... just a thought.