From Guild Wars Wiki

Warning: Running Guild Wars on a non-Windows operating system, or with any other computer which does not meet the system requirements, is completely unsupported by ArenaNet and NCSoft.

[edit] Installing Wine on Gentoo system

Use the following command to download, compile and install Wine Gentoo system:

emerge wine

Continue on Guild Wars on Wine to complet the GuildWars client installation.

[edit] Gentoo notes

You may need add your user acount in the video and audio group before using Wine.

[edit] Running Guild Wars on a separate X server

Once Guild Wars is proprely configured you may create a starter script that will create a new X11 server and use it for Guild Wars uniqly. Do to this create a new text file named GW-1.1.3 and fill it with:

#!/bin/bash
export PATH=/usr/local/wine-1.1.3/bin:$PATH
X :1 -ac & DISPLAY=:1 WINEPREFIX=~/.wine WINEDEBUG=-all wine "C:\Program Files\Guild Wars\Gw.exe" 

And set it allow-execute bit:

chmod a+x GW-1.1.3

Run this script to start Guild Wars with the newly installed wine:

./GW-1.1.3

This should run the game on a new X server, in case of problems press Ctrl+Alt+Backspace to close the game and the new display.