I think you are particularly interested in these class methods (Preview.app dissasembly).
+[NSCursor resizeAngle45Cursor]; which calls +[NSCursor _windowResizeNorthEastSouthWestCursor];
+[NSCursor resizeAngle135Cursor]; which calls +[NSCursor _windowResizeNorthWestSouthEastCursor];
According to disassembly of AppKit these are private methods of NSCursor.
You can try it in your code e.g.
(void)mouseDown:(NSEvent *)theEvent
{
[[self window] disableCursorRects];
id cursor = [[NSCursor class] performSelector:@selector(_windowResizeNorthEastSouthWestCursor)];
[cursor push];
}
There are more undocumented cursors such as
+[NSCursor _helpCursor];
+[NSCursor _zoomInCursor];
+[NSCursor _zoomOutCursor];
and many many more