To set the traders as essential, you need to open the console in the game by hitting the key to the left of your "1" key on the main keyboard - on US keyboards this has the "~" and "`" symbols.
Once you have done that, type the following commands, hitting the Enter key after each line.
setessential 63BF8 1
setessential 63BF7 1
setessential 63bfa 1
setessential 63bf9 1
setessential 69c49 1
setessential 69c47 1
setessential 69c45 1
setessential 69c43 1
setessential 27de7 1
setessential 27deb 1
setessential 27ded 1
setessential 27de5 1
Exit the console with the same key you used to enter it, and you're done.
Note that you only need to enter the first four lines to make the traders themselves essential, but each trader has his own pack brahmin and guard, and the remaining eight lines set them to essential as well. You can still trade with the merchants even if their guards and brahmin die, but IMO it just makes the game better if you preserve them as well.
Once you have done that, type the following commands, hitting the Enter key after each line.
setessential 63BF8 1
setessential 63BF7 1
setessential 63bfa 1
setessential 63bf9 1
setessential 69c49 1
setessential 69c47 1
setessential 69c45 1
setessential 69c43 1
setessential 27de7 1
setessential 27deb 1
setessential 27ded 1
setessential 27de5 1
Exit the console with the same key you used to enter it, and you're done.
Note that you only need to enter the first four lines to make the traders themselves essential, but each trader has his own pack brahmin and guard, and the remaining eight lines set them to essential as well. You can still trade with the merchants even if their guards and brahmin die, but IMO it just makes the game better if you preserve them as well.
Thanks Gator.
I used the option they had at the Wiki, it has the 4 traders made essential, but also has a few other things as well. For example, it has PRID 63C05 as the top line. I'm not sure what those ones are(there's also PRID 63C06, PRID 63C07, PRID 63C08). I am such a newb! LOL!