SQLite does not support encryption or passwords. There are a few extensions that add the capability for encryption, among these are The SQLite Encrytion Extension (SEE), SQLite-Crypt, wxsqlite3 and SQLCipher. However none of these provides with the tcl bindings to be able to manipulate an SQLite database from tcl code.
I will show you how to achieve this, but it will take a bit of work. You need to download MinGW/MSYS, OpenSSL and the SQLCipher source code. After that follow these steps:
These will create an sqlite3.exe and sqlite3.dll with tcl bindings.
When trying to encrypt a database just type:
PRAGMA key = 'password'
That's all.