Installing the new driver shim automatically upgrades your existing driver, because the 1.0.1 version of the driver refers to the same .jar file as the 1.0.2 version of the driver. Similarly, your changes to the mt_files directory, such as customizing templates, are preserved, and the 1.0.2 version of the driver points to the same directory as the 1.0.1 version did.
If you are using the driver to send e-mail in languages other than English, consider using the new charset attribute, described in New Features.