Solaris 9+ and Nohup

How to deattach a long and already running process from it's shell (or parent process in general) so that it can be left running on the system intact, even if the user who triggered the process logs out? Nohup does it (assuming it's the right version):

 $ nohup -a -F -p [PID] 

These nohup(1) extensions seem to be only available on Sun Solaris 9 and up.