daemontools: nice value in a run script

hello daemontools users,

I would like to use daemontools for watching services under soft real
time (audio) constraints, how do I write a run script with a nice -10
prepended:

kindalike:

--8<--
#!/bin/sh
nice -10 whatever_jack_client_needing_prio_scheduling arg1 arg2 arg3 ...
--8<--

would need some kind of niceminus10andexec tool :-) or is there a way
without writing it.

I'm on OSX.

Thanks.