We have answered you via email 3 times now. I guess we will do it here too...
There is no way for you to type the coordinates in. You could create a KML file using these coordinates and import that. Once it is in KML format you could either just use the locations as a guideline for laying out a flight or you could use it to plan a linear flight directly by appending "_boundary.kml" to the filename.
Draw a line string in Google Earth. Save the KML. Edit the file manually using Notepad or something to include the coordinates you want.
Name the file "FILENAME_boundary.kml".
Follow the instructions here: