LG245 key mapping?

Got a new (Telus) LG245 and would like to know how to make any pad key a hotkey.

For instance there is an icon on the # key for a "padlock" but just how do I program that key to make that security feature work? ie: security-lock the phone quickly when I'm away from it.

Going into Settings > Others > Nav. Key Shortcuts - only sets the navigation key to a submenu, not any hotkeys.
User manual doen't explain remapping keys.

Thanks.