1. Download and install AutoHotKey
3. Modify AutoHotkey.ahk in notepad, adding these two lines. The second line allows you to still use capslock, but it is now mapped to Shift+CapsLock.
Capslock::LButton4. Make other desired changes or removals (see their documentation)
5. Re-run AutoHotkey
6. Make AutoHotkey run every time you start you computer by adding a shortcut to your script to the start menu startup folder, as described in the AutoHotkey FAQ: