How to add actions/functions to wearable objects?

Yes, you will have to clone the original EA interactions though and replace the animations with a glasses one, as well as other stuff as the interactions are on the sim so there will be other differences like identity tests. So:

1. Find the interactions you listed that you want to add and add them to your package. Make them custom, tutorial here.
2. Find at least one glasses interaction to compare to (one is computerGlasses_Browse_Web), replace the items in the test_globals of your custom interaction with the glasses one, replace the animation mentioned in the file as well. That should hopefully be all you need to do.
3. Add the interactions to the glasses trait. Unfortunately XML Injector doesn't handle injecting interactions to traits so you will need to override the trait (file is trait_ComputerGlasses_Wearing), or add a trait test to your new interactions and then use XML Injector to add to sims.