I think you're mixing up two concepts here:
1) "how to control the density/resolution of an exported LWO mesh?" relates to exporting geometry from TG2.
If you want to export geometry you need to calculate the mesh at rendertime and thus render the actual image.
The detail setting controls the amount of subdivisions the renderer uses to calculate the terrain.
The more subdivisions the more triangles and thus the denser the mesh.
Usually with a detail setting of 0.3-0.4 you already get a very dense mesh.
You'd need to experiment with this a bit to see what fits your needs.
(btw, if you use this then you don't need any GI/lighting/atmosphere so you can disable all of those for superquick renders)
2) the quote from Oshyan explains on how you can control resolution in a TG 2 generated heightfield.
DutchDimension just explained to you where you can do that.
I hope this clears things up a bit.
Cheers,
Martin