Are you talking about the the deinterlace filter from DScaler? It works in Media Center.
Try downloading the latest Deinterlace.dll from DScaler and register it on your computer. Under "Advanced Properties" in Media Center TV configuration, you should see a Deinterlace option.
Years back I made it work with MC. At that time I had to fix some bugs and build a special version of it myself. I hope Dscaler has since fixed the bugs. I no longer have the version I built. But there should be one somewhere on JRiver's server.