I have tried the Image command using dynamic positioning. It seems to work for horizontal lines but I can't seem to get it to work for vertical lines. The box I want to create is around a customer field in VA01, the vertical lines are at:
Image (0.5,16.5) (0.6,27.5) "red.gif" -plain
Image (1.5,16.5) (1.6,27.5) "red.gif" -plain

with

Image (0.5,16.5) (0.6,27.5) "red.gif" -plain

Image (1.5,16.5) (1.6,27.5) "red.gif" -plain

Image (0.5,16.5) (1.5,16.8) "red.gif" -plain

Image (0.5,27.5) (1.6,27.8) "red.gif" -plain

you get a box around the field.