Is it possible to create an installation pack in Drush make? I already have a Drupal 7 running. Is it possible to create an installation package using Make from my current setup. My goal is I have a Drupal 6 version which I need to convert to D7. For the sake of automated deployment I want to replace my D6 core once finished running the scripts to disable modules, features, and custom theme with my Drupal 7 setup before running update.php.
I have code to generate an installation profile from an existing site; it is still a work-in-progress in the issue queue here: http://drupal.org/node/1368242.  Presently it works with D7, but does not yet generate the necessary installation scripts for D6.  It still does a lot of useful work for you, though, and is a good place to start.

However, if your goal is to upgrade your D6 site to D7, what you are really looking for is Drush Site Upgrade.