如何在WIX Bundle中使用CustomAction ?

To give you a background - I have a 4 MSI's which comes from our vendor and this has to go to our company servers (we are looking at around 3500 servers). As of now, my counterparts are managing this using vbs, ps1 scripts. But the problem with the script is that everytime an update comes we have to worry about uninstalling the existing package before running the new one and a ton of hardcoding. To give you a background - I have a 4 MSI's whi