After looking around for a bit of info about producing a Harris Shutter Effect in post-process only I had a play around in X4 with a couple of Multi exposure shots.
Both pics were produced with a Fujifilm S9600 bridge camera and PhotoPaint X4. I used 3 closely timed exposures of each shot layered in X4 using RGB source merge modes (seperate channel for each exposure)
The first one is a bit of an extreme effect but I kind of like it. I used a Circular Polarizer and ND Grad filter.
This one is a more sedate shot of water flowing through some sea defences. This demonstrates the effect better I feel. The only filter on this was the Circular Polarizer.