EM-COP allows you to enter a grid reference to locate a position on the map. You can also click on the map to get the 10 digit grid reference for the point you click.
On the Situation tab, start by going to Geocode Location button (the magnifying glass icon above the +/- zoom icon just under the Workspace button at the top left of the window.)
To locate a position on the map using a grid reference:
From Geocode Location, select "US National Grid System / Military Grid Reference System" and enter a 6, 8 or 10 digit reference prefixed with the Map number.
You can quickly find the map number by turning on the MGRS Grid layer via Data => Map Grids => MGRS.
As an example, locate the State Control Centre as follows:
6 digit: 55HCU216135
8 digit: 55HCU21611351
10 digit: 55HCU2161413506
To get a 10 digit grid reference for a point on the map:
From Geocode Location, select "Reverse Geocoding" then select "US National Grid System/MGRS" from the drop-down (there are also various degrees options as well)
Click the "Locate" button then click a point on the map. The MGRS is returned in the box below the Locate button.
You can convert this back to 8 or 6 digits by splitting the 10 digit reference into two 5 digit groups and dropping/rounding the last 1 or 2 digits from each group.