Deploy .mst file with GPO

Hello,

I am looking for some advice on how to deploy my newly created transform file using group policy. I have read a great deal on Microsoft on this, but I guess Im just not finding what Im looking for. Im missing on how the .mst file fits into group policy. Im fully aware on how to create the mst, as Ive already done that. Im also fully aware on how to publish/assign applications. When setting up a new GPO, the only option is to point to the .msi file. That is where my confusion comes in. How do I tell the GPO to look at the mst file?

Thanks.