You don't add this to the ACE component. Nor to the framework.
You need to add CSS at application level to enable alternating row styles.
ACE doesn't suggest changing the theme used dynamically, and if so restricting the available themes so you can detect the theme and use different app level CSS tailored for each of your selected themes.
The application developer, when adding alternating row style will need to decide on what colour best suite their design; as the jQuery theme framework embedded in ACE doesn't provide enough styles/colours/states us to represent the differences between hover state / selection state / editing state / alternating row style / disabled state, and so on. Thus the application developer has to tailor CSS styles for a few features, should they decide to use them, for each theme they decide to support.