The other difficulty with a password is that it takes at least 2 keystrokes per character to enter any kind of alphanumeric string. I don't that anyone would use the feature for very long. Spend some time using the 'Find' feature and you'll see how much of a pain it is.
How about this as an alternative? You can enter your name, phone#, etc. on the Welcome screen, and that would very difficult to get rid of without a manual or software.
Another alternative would be to keep a dummy V-scanner file in active memory when you're not using the radio. When you're actually using the radio, simply load the V-scanner that you really want to use. You could do this much faster than you could enter a password.
Admittedly neither of these ideas are 100% secure, but they are easy to do and could only be defeated by a user who is knowledgeable about the radio.
73/Allen (N4JRI)