Adding any layer to the planks will cause an imbalance in all your trim. Door facings will need jamb extensions, trim will need to be removed and replaced over the new covering. Really a PITA, as opposed to removing the planks and installing sheetrock.
I"ve never done it, but you may be able to skim coat the planks depending on what they look like. Can you post a few pictures so we can see what you see?