Yes you should be able to use Overture with Kontakt, though it is not nearly as simple as GPO Studio (also you will likely lose the ability to use special GPO features in Overture, if you plan to use GPO in Full Kontakt).
To do it, download and install Maple Virtual Midi Cable from www.marblesound.com and then go to www.plogue.com and download and install Bidule. There are other midi drivers and VSTi hosts you could use instead, but these ones work very well and are relatively easy to setup. Start Overture and for any midi output that you want to go to Kontakt, route it to Maple Midi Out: 1 (which gives you 16 channels to work with). In Bidule, create a midi input of Maple Midi In: 1, and create a VST instrument of Kontakt, and an audio output (for your soundcard), and connect them together. I won't go into huge detail of setting up Bidule, but after playing around with it a while you will likely get the hang of it. If you need more than 16 midi channels, you can also use Maple Midi Out: 2 (and 3, 4 if you wish) as outputs in Overture, and Maple Midi In: 2 (3, 4, etc) as inputs in Bidule.