The mspdebug commandline tool work with the Launchpad EXP430G2 I have built a CCS 18.3 project and load up mspdebug like this to program the 430G2553
There are docs online for integrating it into CCS but for now the commandline is good enough for me.
I recently found out that Energia 21 will program using the new Launchpad EXP430G2ET but I believe it using DSLite to do that. It's found in the hardware/tools/DSLite directory of the Energia Linux installation.
UPDATE: command to program using Energia's dsli