Regardinng trapping control amiga-amiga.... wouldn't it be just a whole 
lot easier to use a shitdown command that 1) syncs disks, 2) halts 
processes and 3) unmounts any filesystems etc? (not necessarily in that 
order of course) Then once the system is quiesced, call or otherwise 
signal the ados routine that causes a reboot.
 No, it's NOT Ctrl-Amiga-Amiga, but it IS clean and safe.