I have an installer that is supposed to set up a menu item in the context menu of Excel add-ins (.xla, .xlam).
Manually, I know how to modify the registry to get that item which launches my .exe on the selected file. The key has to be something like :
HKEY_CLASSES_ROOT\Excel.Addin\shell\Name of my program\command
With command containing one string of key “(Default)” and value “my exe.exe %1”.
By using the below wizard in Visual Studio installer (to get the location of my .exe which the user can choose to put where he prefers), I manage to place this command just where needed.

Problem is that it also creates another “(Default)” just before mine in the “command” key when I look at the registry. The result is of course that my “Default” is not considered…

From Ken White’s comment: