I've got one of the MSP430FR5739 experimenter boards and have been trying to get mspdebug working on it.
(mspgcc seems to work fine for this part, though I haven't tested the result)
Currently I can run the program and get possibly correct register outputs, but programming doesn't work yet.
Attached are some usb sniffs from code composer studio talking to the chip, if that helps anyone.
I also sent this to the guy who wrote mspdebug, and have heard of other people contacting him, so maybe he'll get around to adding this soon.
usblog.zip