Judging by the sample wav at the end, someone might be able to use Software Activated Mouth. They sound pretty much identical, so I assume Commodore either used the DEC voice engine, or modeled after it.

They share the exact same abilities as well. There is a manual that describes how to get every possible phoneme out of it. Instead of spelling like normal words, there are letter combinations and numbers to denote pitch and speed, etc.

I wonder if anyone had tried to get it running on Wine. If they have a working Windows binary, it should work just fine for decades to come.