With my earlier Gnome Desktop Environment, switching gtk2 themes was a breeze. Now that I'm using openbox wm, I can't seem to find a similar method.

If the required tool can be found in Gentoo's portage, that would be great.

It would also be neat if the tool allows me to change font size (to keep it consistent with the rest of my desktop.)

p.s. The theme I'm interested in is industrial-myst.