NAT IPFilter

Hi everybody,
I'm running on Solaris 10 X86 (update 1009).
I would like to make NAT's rule. I explain you.
On Solaris, I configure the principal interface e1000g0 with IP : 192.168.0.33

I created the first logical interface like that :

ifconfig e1000g0 addif 192.168.0.40 netmask 255.255.255.0 up 

and the second like that :

ifconfig e1000g0 addif 192.168.0.41 netmask 255.255.255.0 up 

I have on a Linux Redhat 5.4 a FTP server and a WEB server with IP 192.168.0.1

What I wanted to do, is to map the address 192.168.0.33 to the logical 192.168.0.40 when I connect to the FTP on 192.168.0.1 and to map the address 192.168.0.33 to the logical 192.168.0.41 when I connect to the Web server on 192.168.0.1

I know how to map :

map e1000go 192.168.0.33 -> 192.168.0.40

But I don't know how to map to the logical IP address according to the port 21 ou 80

I look to the man page of ipnat but I don't know if it's possible