This question's been bugging me for the last few days, but I can't really find an answer other than there was probably some direct sort of royal administration (like Jerusalem). You might have some luck browsing through the Assizes of Jerusalem for a reference, though.

I see Joscelin of Courtney listed as a governor of Acre in an essay from John France. Joscelin the III was also a seneschal, so there's probably some overlap between the two positions, but I'm unsure if this was always the case. Unfortunately Joscelin III was seneschal two years after the death of Baldwin IV.

I'd be interested if you could find an answer, though!