ipnat rdr rules on the same segment?

[mel kravitz <mel@switchpwr.com>]

Can ipnat (rdr )redirect port 80 from www(x.y.z.b)machine to
FW(x.y.z.a)machine when both reside on the same outside segment? Is a
rule such as the following possible?
rdr fxp0 x.y.z.b port 80 -> x.y.z.a port 80
-Mel