Yep, it is quite possible. You want to use the -image command.
Install the Guild Wars client. Once you have it installed, close it up. Go to the shortcut you use to open Guild Wars. Right click the shortcut. Click properties. You should see a window that has a Target: bar on it. Inside the target bar, you will most likely see this:
"C:\Program Files\Guild Wars\Gw.exe"
All you have to do is add the -image to the end of that, apply it, and close the box. Then open Guild Wars via that shortcut. The client will now download every single file the game has, and completely construct the gw.dat file to full size. You will have every map, skill, texture, etc the game has.
The target bar should read like this:
"C:\Program Files\Guild Wars\Gw.exe" -image
When it is all done, simply go back into the window by right clicking and going to properties. Remove the -image part, and apply the settings. Close the properties box, and run Guild Wars normally. Tada, done!
The wiki article Gifted posted above will essentially tell you the samething. If my post confuses you in anyway, try reading the wiki article.
