If you have already participated in a previous PTS session and still have the client installed, you will only need to apply the latest patches. Otherwise, accessing the PTS will require that you download and install a separate instance of the MWO client.
The download link for the PTS installer can be found here.
For detailed instructions regarding the installation of the PTS client, please consult the main post for PTS2.
Please do not submit any support tickets regarding issues with the Re-Balance PTS.