Is there a way to increase the dimbox cell size?

In OPIM, when extracting isometrics with angled lines, the program puts in two dimension lines with a small square in the corner to show that this is an angled line. The cell for this square is called Dimbox. This cell is so small that it's hardly noticeable on the isometrics. I can't find the cell in our isometric library so I assume it's hard coded into the program.

Is there any way to modify this box so I can adjust the size of the cell for all of our isometrics?