You can enable port forwarding on the Administration -> System page if that's what you are referring too (forwarding a local port through an SSH tunnel). That can then be used as a quick'n'dirty VPN, where your SSH client could redirect local port 8888 to a remote port 80 (a NAS, for example).
Asuswrt-Merlin: Customized firmware for Asus routers
Github: github.com/RMerl - Twitter: RMerlinDev
See the sticky post for more info.