How to use Masonry Stamp in Wallpress

I’m trying to use the Masonry stamp method in Wallpress.
In a perfect world I could assign a post as ‘stamped’ in page editor and control it with css – and would pay to have this plugin made but for now…
I’m trying to figure out what to edit to activate a single stamp in the top left corner of the homepage and specify unique stamps on other pages.  I’ve read the masonry docs and the forums here as well as a thorough search through the template files.

1. First question – How do I ‘stamp’ a specific post as ‘stamped’ so I can even see if I’m making progress?

• DW Wallpress 1.1.7
• jQuery Masonry v2.1.03

In v3 of masonry the stamp has been overhauled – is it possible/advantageous to upgrade without damaging the template?
Thanks!