Okay, I am not too clear on the last part, but saving the coordinates to an Appvar I can do:
.0:Return
Send(4,"UCoord→V
{V→X
{V+2→Y
Repeat A=15
iPart(V,X
iPart(V+2,Y
Line(X,Y,6,6,2
DispGraph
Line(X,Y,6,6,2
Repeat A
getKey→A
End
X+A=3
-A=2
-A=5
+A=6
-A=7
+A=8
If >90
X
→X
Y+A=5
+A=6
-A=7
-A=8
-A=4
+A=1
If >58
Y
→Y
End
Stop
That will move a rectangle around the screen saving the coordinates to the appvar Coord. To be honest, though, you only need two bytes for the coordinates here >.>