How to install/enable Enhanced Dictation automatically?

Question

Mavericks has a new version of the Dictation feature previously available in Mountain Lion. In Mountain Lion it only worked by (like the iPhone) sending speech to Apple's servers to be processed and therefore required a live Internet connection. Mavericks supports this same mode still, but also now offers an 'Enhanced Dictation' mode where the processing is done locally on the Mac itself and therefore does not require a live Internet connection.
The normal way to enable this Enhanced Dictation mode is to open System Preferences, click on Dictation & Speech and tick the options to turn on Dictation and Use Enhanced Dictation. This will trigger a download and installation of the required software. However as should be obvious this requires manually intervention to do this. If one is wanting to build a number of Macs with this feature enabled this rapidly becomes tedious in the extreme.
Is there anyway to manually download an installer which can be run on Macs to do this? If not is there a way to write a preference e.g. defaults write which would trigger this automtically? Either approach could then be incorporated in an imaging process like DeployStudio.

Answer 1

I don't have a Mavericks machine handy right now (I am currently at home) but the following information should help you.
First the link I provided is for the UK language version, there will be different but presumably similar links for other locations, e.g. USA, Australia, etc. You will need to do the samething I did to find the right link for you I am afraid which is run a packet capture to spot the URL System Preferences starts to download, I would guess most or all will contain SpeechRecognitionCoreLanguage but searching for http://swcdn.apple.com would be another option.
Second, your right, after installing it you also need to set via defaults some preferences. Again not having access to a Mavericks machine right now I cannot tell you the exact settings, but I would look in both /Library/Preferences and ~/Library/Preferences for files relating to speech recognition. Perhaps have both these folders open in the Finder in list view.
I would then in System Preferences turn on the options for Enhanced recognition for your country, yes this will start a download which you would need to do anyway for the packet capture as described above. This will also put the correct settings in the appropriate plist file. You should then in the Finder be able to see which file just got modified, this will confirm which file contains the settings.
You can then run -
sudo defaults read /path/to/file/com.apple.whateveritiscalled
This will read and display all the settings in that file. You can then see which ones contain the settings you need. I think from memory there are two settings you need to look for.
You could stop the download which is done by turning off the settings in System Preferences. You can then manually download the file presumably having found the URL in the packet capture. You can then do
sudo defaults write /path/to/file/com.apple.whateveritiscalled whatevertheprefiscalled whateverthesettingis