Super Zoom?

Many MW DX-ers use offsets from nominal frequency to determine the number of stations on a frequency and tentatively ID them (and actually finding new stations!). Frequency offsets are measured in Hz and they are surprisingly stable from station to station. With GPS calibration, the Kiwi should be accurate enough, so the question is: Is it possible to make a "special zoom" to allow for a spectrum of, say 20 Hz? We routinely use this on the Jaguar software for Perseus. SDR Console has a similar, albeit less flexible solution.