Without the ETA there is no "climbing mode" which pretty much means no lockout. ETA lowers the fork height and locks it out (makes it stiffer for climbing).

As far as installing a fork goes, I personally did it myself and I found it very easy. Basic tools around the house and a hacksaw and pipe-cutter was all I needed to install it. Some will suggest you bring it to a shop to do it, but all I'm saying is that it's easier than you think so long as you're mechanically savvy.