To add your preference to the View>Source option in Internet Explorer, go to Start>Run, type regedit. Navigate to:
HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer
Right-click on the Internet Expolorer key, choose new>Key, name it View Source Editor, right-click on View Source Editor key, choose new>Key name it Editor Name, right-click on (Default) in the right pane and type the name of your editor (for example I use Textpad.)
As long as the application has an entry under HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\App Paths, you need only provide the name.
If it doesn't have any entry you'll need to enter the full pathname (for example,) "C:\Program Files\TextPad 4\TextPad.exe"
reghakr