Personally, I try the simplest method. I will take a shot with the grey card in the picture. In CaptureNx (or whatever you're processing your RAW file in - I'm obviously speaking Nikonese), you'd use the card in the picture to set the grey point. Then I use batch - copy settings (the settings are in the clipboard) - then go to your photos you want to adjust with same WB and paste the settings from the clipboard.
Or... you can set a specific WB setting by photographing the card only and using your camera method to set WB.