I see that their template files use a .mcw format, which I've never heard of (and my Mac doesn't recognize). But the task seems fairly simple:
1) Measure the insert space (height, width)
2) Open Word or Pages, and draw a rectangular shape that matches the insert space. Give it a thin border and no fill.
3) Create a text box, and overlay that onto the rectangle.
4) Duplicate that rectangle down the page, so you can fill out more than one at a time.
5) Save it as a template.
Perhaps even easier would be to use a spreadsheet. You can fill in the columns and then just print and cut to fit.
Good luck!