I have created a package with a temporary rule that has all of those "hidden" actions to set the date field. I have found that this is the easiest way to get the date field in the action tab, by copying these actions to another rule.
The way I got them into this rule is by editing the xml file in the package. I put all of the date fields that I thought would be needed in future rules.
As you can see below I have put the EPOCH time in all of the the fields. Just copy this into another rule and delete the fields that don't need. You have to be careful in all other updates you make to this after you have added the date field because if you do it wrong you could remove the field that you previously added.
Let me know if you have any questions how to make this work for you.
This document was generated from the following thread: Need dates in your actions tab?