Go to MSI Script. Select the Execute Deferred tab. Scroll down to the bottom. Drag & drop an Execute Program from Destination action and place it just before InstallFinalize. The tricky part is what to plug into the dialog to make it work, and this is because of the various locations of regasm.exe based on the versions of .NET installed and what your app requires. Finally, wrap the action in an If NOT Installed condition so it doesn't run during a modify or uninstall operation.



Edit: This is but one of many ways to do this. If you are a developer, you could write some vbscript to run regasm and then use a Call VBScript custom action, or a DLL to do it or even WiseScript. There are several choices for you.