Well, inverting the framebuffer can be done, with or without hardware support, but it is not an easy task, and hard to impossible to guarantee that your inverted frame is never shown longer than 1 frame.
If you are using Win32 APIs to draw your graphics, it would be an option to render all graphics into an intermediate frame buffer which is not visible, and blit this buffer either inverted or not-inverted to the actual framebuffer.
While writing this message, I checked the T30 Reference manual and might have found an easier solution:
There are hardware registers to invert each digital display signal:
0x54240c18) and following.
You can try to run a parallel application which does continuously
Configure Display signals to be inverted
Sleep (59 * 60);
Configure Display signals to be non-inverted
To write to the registers, you can use the MapMem Library, which is part of our Toradex CE Libraries.
There’s no simple way to synchronize this operation to the frame-sync, so you might change the polarity in the middle of a frame. However, if your display is slow enough that such an effect is not visible, the synchronization should not be necessary anyway.