I could be wrong, but i believe that because pdf requires you to run a reader, you can't import the pdf directly within your content.
However, I think an iframe might work for you. You can retrieve a pdf file via ajax, I'm sure. It's just a matter of getting it displayed once you get it. The only way to figure it out I think is to try. If ajax to a div doesn't work, try an iframe and target to that.
