How to su root on Solaris?

I'd like WinSCP to be the root user, but I can't log in remotely as root. So somehow I need WinSCP to su root. I saw this in the FAQ -- you can do something like

/bin/bash -c 'sudo su -'

and then there is some configuring involved.

Trouble is, I'm a Solaris newbie, and sudo doesn't seem to be installed. Can anyone give me easy instructions on how to do it in Solaris?