page sizing and handling default options

I need to set the "Fit" option (under the size tab in print dialog) for about 5000 machines, but cannot find a way to do this.  There does not seem to be a regkey for this, and I'm trying to see to what files acrobat reader is writing in process explorer.   but nothing comes up.   Still it seems to remember the last chosen option there so it must be possible to make it persistent I think.  Anyone here had the same issue and solved it ?
Oh, I also tried the configuration wizard that is no help either...