First install Battle Symphony following the instructions.
Then add this script below Battle Symphony in the script list.
Copy the required MV battlers into the Graphics/Characters subdirectory in your VX Ace project.
You will need to add note tags to your database, to specify which battlers to use for each actor and enemy. Without this tag, the default battlers will be used.
<MV BATTLER: file>
The MV format has separate animations for THRUST, SWING or MISSILE attacks. To specify which motion to use when Battle Symphony calls for an ATTACK animation, use the following note tag on actors, enemies or weapons:
<MV ATTACK MOTION: keyword>
See the user guide included in the comments at the top of the script.
This script is released under the MIT license, the same open source license as Battle Symphony itself.