In general how I do it:
@overlay BLOOD OVERLAY 01 creat
@overlay BLOOD OVERLAY 01 opacity 1 in 0
than in preview I look in the scene and move and scale the overlay to the place I need it to be (do you know how to use the preview window to adjust overlays?)
If I am in another zone than 1 I do not see it but still can move it there in preview.
Then I copy the shift and scale command through copy button ( and add the tone if it is in another zone than 1)