I haven't used Toolbag 2, but for TB1 there is no way to get a true orthogonal view. However you can get it pretty close by hold down shift while rotating the camera to snap it into the right rotation and setting the FoV (under Render) to something small like 3 (anything smaller will make the model flicker).
set up three cameras, call them front, left, back.
move the front one out in front of your object, rotate the left one 90 degrees and move it to the left of your object, and then rotate the back one 180 degrees and move it to the back of your object.
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move the front one out in front of your object, rotate the left one 90 degrees and move it to the left of your object, and then rotate the back one 180 degrees and move it to the back of your object.
change the field of view for each camera to 0.
that should be good!