You can do that! Double right click on the card in the UI, it is a bit temperamental though and seems to be sensitive to the delay between the clicks!
(note added later: single right click works but it is more like a click-hold-release)
Thanks for the reminder about the 'cone of vision' on the mini map, it does indeed indicate the location of the unit under the cursor in 3d mode, but it is sometimes difficult to see the cone when there are several corps deployed on the map and are crowded together as occurs in the montebello scenario. I think it would still be useful to have an indication of which corps flag is the corps to which the unit belongs at a glance so as to see how far the unit has wandered away from its commander.