Symantec WINDOWS INSTALLER EDITOR 7.0 SP2 - REFERENCE FOR WISE INSTALLATION EXPRESS V1.0 Installation Manual page 335

Merge Modules and Transforms
CmdLine=TRANSFORMS="TransformName.mst" /i
where TransformName.mst is the name of the transform.
When you double-click the .EXE file, it reads the .INI file of the same name. (Example:
Application.EXE reads Application.INI.) When it runs the installation, it applies the
command-line option specified in the CmdLine property and the transform is applied.
These command-line options are passed to msiexec.exe, the Windows Installer
executable.
If you have multiple transforms, you can make multiple releases, and manually edit the
.INI file for each release.
Windows Installer Editor Reference 335