Hi..
you can do a static port redirection.. Heres an example:
object network obj-10.10.10.10
nat (inside,outside) static 20.20.20.20 service tcp 8080 80
The above example is showing that clients will use 20.20.20.20 port 80 to get to the server 10.10.10.10 on port 8080.
You can adapt the above to your specific needs.
let me know if that is what you are looking for.
-scott