ipfw forward command?

[hugle]

Hello.
As I understoon, ipfw's forward command goes before ipnat
How i can make it go in some other direction (ipnat then ipfw fwd)?
cause firstly I'd like to NAT packets and then forward them to needed
gateway. But since forward happens before NAT this can't be done, and
packets don't get forwarded to needed gw
default gw x.x.x.161 ip x.x.x.162
second gw x.x.x.141 ip x.x.x.142
third gw y.y.y.1 ip y.y.y.59

Any ideas?
-- 
Best regards,Hugle