TrenchBroom is a free (GPLv3+), cross platform level editor for Quake-engine based games. It supports Quake, Quake 2, and Hexen 2 and runs on Windows (XP and newer), Mac OS X (10.6 and newer) and Linux. TrenchBroom is easy to use and provides many simple and advanced tools to create complex and interesting levels with ease.
Although this TrenchBroom profile and guide is mainly intended for Blockland, there is no reason why it wouldn't be inherently supported for other Torque games. This is why the profile was called Torque and not Blockland.
All instructions have been moved here: https://github.com/ShockFromBL/TrenchBroom-Torque/wiki