If you know how to edit the registry you can search for the Mp3tag entry and change the value of the "Command" key from i.e.
then the folder is loaded.
Or you make a second key so you can choose from both methods.
Method without registry
Open Windows Explorer. Choose Menu "Tools > Folder Options..."
Go to the tab "File Types"
There's the list "Registered file types:"
Find your desired Extension e.g. MP3 (you can press "M" to find it faster) and select it.
Now click on "Advanced" (on the bottom).
Select the entry "Mp3tag" and click "Edit"
You should see a command like this:
"C:\Program Files\Mp3tag\Mp3tag.exe" "/fn:%1"
Just change it to
"C:\Program Files\Mp3tag\Mp3tag.exe" "/fp:%1"
Confirm everything with OK.
You could also leave the standard entry alone and create a second entry for Mp3tag.
Then you have the choice if you want to load a single file or a complete directory.