If you have some specific ICall IDs you wish to listen to, you can treat them like regular talk groups by adding 700000 to the decimal radio ID. For example, if you know radio ID 5051 is one you wish to listen to when using ICall, program in 705051 in as a talk group (along with any of the regular talk groups), make sure ICall is turned on for your system, and go into ID Scan mode.
As soon as you change from ID Scan to ID Search, however, you'll get all the ICall traffic, and will already be displayed with the 700000 mask. That may help when you're trying to ID specific radios you wish to monitor.
UniTrunker will help you ID the radios using specific talk groups, too. Some systems have radio IDs clustered, some not at all--which makes specific ICall monitoring a bit difficult. Over time you'll get most of the IDs you might want in specific areas.