If it works in the Pismo, it should work in a Clamshell. Double check the positioning of the ATAPI connector, some do vary in their positioning. In fact, you'll probably find it easier to test in the Pismo as you only need take apart the plastic enclosure it comes in, and not have to tear the machine down nearly as much as you could in a Clamshell. Also keep in mind you may have to force master/slave setting.

Obviously in both you'll have an ugly bare drive visible, but you could consider slicing the existing fascias to fit a slot CD into.

I've come across so many dead PC laptops with tray-loading DVD burning drives though that it's easier and cheaper to find one of these and put them into the Macs in question. Both plastic fascias needed slight adjustment of the eject button.

JB