Did you had a look at the work of Colin?

   http://map.squeak.org/package/8830dcdc-9329-4190-80cc-dc614c55f3e0

In the description it says:

"SystemEditor is a mechanism for atomically loading a set of changes
to the system. It's intended to be used by tools such as that move
classes (or parts of classes) between images, such as Monticello,
Monticello2, change sets, fileIns etc.

It provides a familiar interface for making changes, but does not
execute the changes until it receives a #commit message. This makes it
easier to update existing tools to load their changes atomically."

-- 
Lukas Renggli
http://www.lukas-renggli.ch