cscreen

cscreen -i <DisplayID> -d 32 -x <width> -y <height>

my:

cscreen -i 43021f6c -d 32 -x 1024 -y 768

cscreen -i 43021f6c -d 32 -x 1920 -y 1200

HomePage:http://www.pyehouse.com/cscreen/

source for setup:https://apple.stackexchange.com/questions/73177/how-to-change-resolution-when-using-screen-sharing-and-no-physical-screen-is-con