You can use command redirection with
& to execute a proceeding command after the first command completes. You can set it to execute the proceeding command after the first command was successful, or directly after the first command executes regardless of the first command result.
The trick is to have the batch script put the VB msgBox function and applicable values it uses into a temp script that will later be executed via wscript.
This should all work out of the box without installing any third party tools so it's Windows native.
Note: You will need to use the syntax of
SET x=msgbox "%TITLE%",0,"%MESSAGE%" rather than what you have for this to work but that's a minor adjustment only.
SET COMMAND=rmdir "%TARGETPATH%
SET TITLE=This is my message title
SET MESSAGE=This is my message body
SET x=msgbox "%MESSAGE%",0,"%TITLE%"
%COMMAND% && WSCRIPT "%tmpmsgbox%"
commandA & commandB Run commandA and then run commandB
commandA && commandB Run commandA, if it succeeds then run commandB