In the version ipscan-3.0-beta4 the set of available options at command line seems to be limited.
I would suggest to add the following options directly from command line,
in order of priority (from my own point of view):
1) maximum number of threads;
2) number of ping probes;
3) ping timeout;
4) multiple non-consecutive ip ranges, e.g., from x.x.1.1 to x.x.1.255 and from x.x.50.1 to x.x.50.255;
5) do not display the GUI.