If you have a need to enter coordinates as longitude/latitude values, then read along as we explore how to do this. 

Before you can enter datapoints in longitude/latitude, a valid geographic coordinate system (GCS) must be assigned to the model.   This can be done by choosing Tools > Geographic > Select Geographic Coordinate System.  For detailed information please refer to the following wiki article:  

Assigning  Geographic Coordinate System

 

 

Once the model has a valid coordinate system, it will appear in the Auxiliary Coordinates dialog where you can then assign it as the active auxiliary coordinate system.   To do that, simply double-click GCS entry in the Auxiliary Coordinates dialog.  Note, you can get to this dialog via the Utilities menu item.

 

 

The next step is to turn on the running coordinates field by issuing a right-click anywhere on the right side of the status status bar.

 

 

Then set the read-out  to ACS Position by doing a left click in the running coordinates field.  You should now see longitude/latitude values in the running coordinates field. 

 

 

 

In this example, a marker will be placed at longitude -114° 03' 46.83 and latitude 51° 02' 39.48'' which happens to be the location of a highly visible landmark in Calgary, Alberta.  To enter the datapoint at that precise location, simply keyin point acsabsolute [longitude, latitude].    Note that the coordinate format can be expressed a variety of ways which are outlined in the wiki article referenced above.For example: 

point acsabsolute -114:03:46.83,51:02:39.48

OR

point acsabsolute -114.063008, 51.0443

 

To add the elevation, simply append the Z value.  For example, point acsabsolute -114.0638008, 51.0443, 500 will place the element at an elevation of 500m.

To verify your work, just export the contents Google Earth. To do that, choose File > Export > Google Earth and enter a file name.  Once created, Google Earth will open and fly to that location.