 :::What you'll need is two sandbox pages, essentially.  On one, you'll copy the template code, and on the other, you'll transclude (use) the template.  For example, I just copied the template code to , then I made another page, , and used the infobox on it... but instead of , I typed {{}}.  Now I can edit the infobox code on the first sandbox page, and see how it affects the infobox on the second.   