I'll take a shot at it bongo (like the handle) don't really understand the question cause you made a simple question LONG and complicated. But what you saying is you want to convert(1)/create(2) a icon to replace an existing one. Simple! yes.
Here's what you'll need:
(1) Axialis Iconworkshop
(2) Photoshop
Install iconworkshop. open it, it'll pick up you have photoshop installed and give you an option to install a plugin. Creation sorted. Now on to replacing the icon. Even easier, can't fully remember iconworkshop's menu system, but mess around, it is there.
If you think this information helped, or even better. Solved your problem. Please add to my rep