NAT - Static NAT

You can do STATIC NAT and just "go out" of the router with a different IP address:
*Traffic sourced from 10.2.2.1 will seem from 131.1.12.3
*Extendable is used if you need 1 LOCAL IP to be mapped to Various Public IPs
(config)#ip nat inside source static 10.2.2.1 131.1.12.3 [extendable]

Be sure to DEFINE the NAT INTERFACES:
(config)#int lo0 <- PRIVATE IP
(config-if)#ip nat inside

(config-if)#int s0/1/0.21 <- PUBLIC (Global) IP
(config-subif)#ip nat outside

#sh ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
--- 131.1.12.3         10.2.2.1           ---                ---

Inside Local - Private IP of the host in your Network
Inside Global - Public IP that outside network sees your hosts as
Outside Local - How the local network sees IP of the remote host
Outside Global - Public IP of the remote host

If you want to do NAT for a SUBNET:
(config)#ip nat inside source static network 10.2.2.0 200.2.2.0 /24