I do them point by point, at the file xm-globe.rul. First, i studied the pattern of the points near a known border and added the rest. Some borders aren't mine, but frankly, i don't remeber what is the basis mod.
But you don't need to do a harder work. There is a program from Falko that allows to do these borders. I haven't used it yet, but i know that it could do that.