From PowerShell or CMD:
cd C:\Program Files (x86)\fournova\Tower\CompareTools
code .
Edit VisualStudioCode.json and replace line 10 which is:
"%ProgramW6432%\\Microsoft VS Code\\Code.exe",
With
"C:\\Program Files\\Microsoft VS Code\\Code.exe"
Code will throw an error saving because it requires local admin permissions, use the "Retry as admin" button in the UI and the file should save. You can now open Tower and select Visual Studio code as your Diff and Merge tool.
On which OS?