By "module loading" they mean the very first time the merchant spawns. So for example, if you were adjusting the inventory for the "crazy rodian" on Dantooine, you would need a savegame before the very first time you exited the Jedi Enclave..
For Nemo's corpse, you would need a savegame before the very first time you entered the ruins... etc. etc.
Once a merhant/npc/etc. spawns for the first time, everything is set. Unfortunately there isn't a 'cell reset' (such as Oblivion) so it can get tricky with placeables in KotOR / TSL..