First build the MIntyBoost kit according to its instructions.
It's really easy to assemble- even a complete novice can do it.
Instead of connecting the battery holder in the kit, we're going to solder a JST connector to the MintyBoost PCB. This tiny connector will then allow the MintyBoost circuit to connect to the Lithium Polymer battery charger circuit. Make sure you get the polarity correct!
Test the MintyBoost by connecting the battery pack (make sure the battery pack has a charge) and charger circuit. The MintyBoost connects to the connector marked SYS on the charger board and the lithium polymer battery connects to the connector marked GND.
Now cut a notch in the Altoids tin for the USB port and use some double sided adhesive to mount the PCB to the Altoids tin.