Overwrite this to the SDRSharp.EXE config file. It will give the extra step sizes (Aviation, NXDN). It's easy to add extra step sizes
Also, you can edit the Band Plan to Step Size 8330 for the desired frequencies..
<add key="stepSizes" value="1 Hz,10 Hz,100 Hz,500 Hz,1 kHz,2.5 kHz,3.125 kHz,5...