Hey...
I feel a little un-easy about making LOD models of standard 3DGS models available to you or anyone...
I figure if 3DGS wanted LOD versions available, they would have made them available already.

If you want to experiment, simply create three different models and name them Something_0.mdl, Something_1.mdl, Something_2.mdl and Something_3.mdl
Then add the Something_0.mdl to your game through wed or sed... you will find that at different distances they will automatically change.

The best model should be _0 and the worst/simplest should be _3
It is possable to change the distance where the models switch.
Read the documentation...
Good Luck....