I wonder if thats possible. Here is the error I get. Not all the flags I use, but just to give you an idea.
C:\x264>x264 input.avi --profile high10 --vf crop:1,0,0,0 -o cropped.mp4
ffms [info]: 523x361p 0:1 @ 24/1 fps (vfr)
resize [error]: resolution 523x361 is not compliant with colorspace i420
Secondly, here is a link which says its not possible to crop 1 pixel.
http://mewiki.project357.com/wiki/X264_Settings#crop
Can you share your code please?