Why would I want to so something so blatantly stupid you are now asking. Simple, because the mod is client side only.
The reason, My son and I play minecraft. I have a gaming PC I have built and he has a hand me down. I tend to like JourneyMap but his computer spazzes out something fierce when he uses it. So if I have JM loaded when I open a Lan Game he can not join because FML rejects the connection because he does not have JM.
So, that is why I ask if I can make open the game to lan with journey map while having it omitted from the server mod check.