In fact, it is as easy as just say it. Under the JDS3 desktop environment and running on Solaris 10+ (at least), you just have to populate your ${HOME}/.fonts directory with your TrueType fonts (which generally ends with a .ttf extension name) and log in again. Et voila: any GNOME/GTK software will be able to use them automatically.

There no need anymore to use other X Window System tools, such as xset(1) or mkfontdir(1).