Charly - if you mean Installer, as in, to add more programs, games, etc.,then you will need to jailbreak your Touch.
The Installer is part of the jailbreaking process. You will need to downgrade your Touch from 1.1.3 to 1.1.1 and then back up to 1.1.3, but with various additions to the system. It is a closed system, therefore it needs to be broken out of jail - jailbreak!
The Installer is part of the jailbreaking process, it can not just be installed on an out of the box Touch.