How to Connect cube vertices with arrowline?

Hi. I have a 3D cube, something like that: h(1) = axes('Position',[0.2 0.2 0.6 0.6]); vert = [1 1 1; 1 2 1; 2 2 1; 2 1 1 ; ... 1 1 2;1 2 2; 2 2 2;2 1 2]; fac = [1 2 3 4; ... 2 6 7 3; ... 4 3 7 8; ... 1 5 8 4; ... 1 2 6 5; ... 5 6 7 8];

patch('Faces',fac,'Vertices',vert,'FaceColor','r');  % patch function 
light('Position',[1 3 2]); 
light('Position',[-3 -1 3]); 
material shiny; 
alpha('color'); 
alphamap('rampdown'); 
camlight(45,45); 
lighting phong 
view(30,30);
And i need to connect 2 of its vertices with line, idealy a arrowline. How to do this?
I need something like this:
<<http://imgupload.sk/images/h/o/hoc6semsl6h93c5sr35m.png>>