I was trying to get something like this for a while, and I think the answer turned out to be removing Acrobat from the registered plugins and then adding it as a helper application. Serious pain to make it work. Ultimately, the problem that was biting me was that Acrobat 6.0, when trying to run as an ActiveX plugin, would sometimes wedge and I'd have to kill it off with the Task Manager. I ultimately solved that problem by downgrading to Acrobat 5.0.