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
mspdebug rf2500
https://github.com/dlbeer/mspdebug
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
