There is no formal mechanism for doing this.
You can use programmable logic to control whether an item is available or not, but the logic needs to be totally self contained in your Info.lua file. See this cookbook recipe for an example of how I use this.
If you are asking whether a user can click on a button and have a menu item become enabled/disabled, can't be done using the SDK. The closest I know of is plugin code dynamically rewriting the Info.lua file to alter menu items defined but this only takes effect when the plugin is next reloaded (or Lightroom is next reloaded).
Thanks Matt .