How to: Create a Custom Action Specific to a List
Create a CustomAction (with GroupId of "ActionsMenu") that is specific to a custom list.
The challenge here is that the custom list is yet to be created and so the RegistrationId property of the CustomAction cannot be determined at the time of installing the CustomAction.
There are problably several ways to addres this task; 2 of which are:
Option 1: Specify ControlAssembly and ControlClass properties for the CustomAction and in the custom control class build the menu item for the CustomAction if the list is the right list. The down side to this approach is that (1) the CustomAction is actually published on all list instances but built only for the appropriate list, (2) there's no way of indicating an identifier for the list without hardcoding its name/url in the custom control class. The upside is that (1) you can easily modify the behaviour of the CustomAction by simply revising the custom control class.
Option 2: Create and activate the custom list and CustonAction using 2 different features one after the other with the feature for the custom list going first. Then using Feature event receiver class for the feature of the custom list, update the element.xml file for the CustomAction's feature; prior to attempting to install and activate it; with the GUID of the list instance you just created. This approach with ensure that the CustomAction you just created is available only in the custom list you just created as well. The downside, however, is that any change to the CustomAction requires a reinstallation & reactivation of the feature.