Do you mean you want to telnet to port 80 to test ?
If so then -
inside host = 192.168.10.1
object network WEBSERVER
host 192.168.10.1
nat (inside,outside) static interface service tcp 80 80
for the acl you can use either the real IP or the object you previously defined, your choice - ie.
access-list outside_in permit tcp any host 192.168.10.1 eq 80
or
access-list outside_in permit tcp any object WEBSERVER eq 80
the above means you telnet to the outside interface IP address on port 80 and it should be sent to your internal host on port 80.
If you want to use a different IP to the outside interface IP then just replace "interface" with the IP.
If you want to use telnet and not telnet to port 80 then just replace the port numbers accordingly.
Jon