I just did a quick Google search for images, and yeah, looks like a lot of people have done shop-made milling attachments (I searched 7x12 figuring more hits.) Is that what you're after?
I have the store-bought version for my lathe, and while it's not terribly robust and a lot harder to use for milling than a vertical mill, there have been a few operations that I did fairly easily that I had trouble figuring out how to handle on the mill. Figure out how to include height adjustment (as opposed to a static mounted vise) if you can. I've definitely used that feature on mine.
-Ryan