how to replace whole category loop for custom content?

Hi. I am using 3.6.4
I am trying to customize the display of my multi post page in categories.
I had no trouble adding breadcrumbs with "before the loop".
I also had no trouble displaying a list of categories when there are subcats, (using a plugin that prevents children from showing up in parent categories) and displaying a list of sub-cats (children) using the " content if not found" .
so far so good.
Now I need to replace the loop.
I want to integrate the output of formidable forms (let's just say my plugin spits out the formatted posts for this multi-post page)

something like if is_category() use formidabledisplay instead of the loop.
tried using "the loop" part but I still get multiple results as we still go through the loop for each post

Any ideas.
Thanks in advance. this is my first post, I love the theme.

P.S. too bad that I am just learning to integrate all this extra php stuff that I know nothing about and now I see the new version doesn't allow it. ouch

Albert in Costa Rica