Is there a particular reason you want the Macs to reboot? Normally a reboot shouldn't be necessary after enrollment, so I'm just curious.
If you're using version 9.x of Casper Suite there is a new option for a policy trigger/event called "Enrollment complete" I believe. You could have a policy that gets triggered by that event which simply forces a reboot, or at least prompts the user to reboot, maybe giving them a small window before its forced.
if you're using version 8.x, then its going to be trickier. In fact, I don't have a good answer at the moment. As far as I know, you can tack additional actions onto the end of a self enrollment, unless you specifically customize the QuickAdd.pkg to do a postinstall script. Only thing is, I'm not clear on how, or if, you can edit the QuickAdd.pkg that's generated off the JSS.
