I created a Github repo on this problem a while back, and came up with a possible workaround. That took the form of Invoke.exe, which would be run before Scripter to trigger the BSL (as in your diagram). But then "drcrane" was able to modify the Scripter source code and recompile to include the INVOKE option in the Scripter Mode command. My repo is:
https://github.com/gbhug5a/CP2102-with-BSL-Scripter-for-MSP430and his is:
https://github.com/drcrane/bslscripter-vs2017He has all the source code, but it's simpler to just use his executable provided in Releases. At the least though, you should read the instructions in the release zip.
None of this is approved by TI, so you proceed at your own risk. I would just say that it's unfortunate that TI didn't provide this option, at least as far as I know. They added suport for their Rocket device, but I don't think that's the same as the generic USB-to-UART devices. But of course you can just buy a Rocket, if you can find one, and use that with Scripter. See SLAU573C.