Kerry writes about using the Launchpad as an external programmer for MSP430G devices. You can do this via SBW or Spy-Bi-Wire using the TST and RST pins, which correspond to the Data and Clock SBW functions respectively.
To program an external MSP430G2 device, you need to simply remove all the jumpers from the LaunchPad develpment board and connect the TEST, RST and ground pins with your target device (see picture below). Since the on-board MCU will be disconnected from the flash emulation circuitry there is no need to remove the MCU from the Launchpad when programming an external device. And the external device does not have to be the same type as the one on the LaunchPad either.
In the picture below, the RxD pin is also connected, this was for my testing purpose and is not needed for programming the chip.According to the reference design, a 47K resistor should be used as the pull-up resistor on the RST pin.