Forcing rdr rules to load

Hello All,

I have a bunch of windows clients running LPR service listening on port
515 behind my IPFilter box (3.4.35) with FreeBSD 4.11 receiving printing
jobs from a mainframe. Each client have a different address, so I have
to add one IP on the outside interface (xl1) to make a rdr rule to this
client (rdr xl1 outside-IP/32 port 515 -> client-IP 515 tcp). So far so
good. Well, while trying to load this rules I get "can't resolv
hostname: client-IP/32, syntax error in "rdr"". It makes sense, IPFilter
checks if this machine is up to load the rule, but these are windows and
sometimes while reloading it may be offline.. there is a way to force
IPFilter to load this rdr rules even if on of this clients is offline?

Thanks.
--
Alexandre Vasconcelos
Unix Admin
SSP/GO