For those using this — I’ve figured out how to get the Access connection to behave better, so now if you will be able to extract as many records as you need to edit and expect all updates to occur. Prior, the plug-in would occasionally error out and an handful of records wouldn’t get changed in the Connexion file. This is fixed. To update the Plugin — open the plugin manager, delete the old Connexion plugin, then close MarcEdit. Next, open MarcEdit, go to the plugin manager and download the updated version of the library. Restart MarcEdit — you are now using the current version of the plugin.
Source files for those interested: http://oregonstate.edu/~reeset/marcedit/software/development/plugins/source/oclc_helper.zip