Muntjacs are awesome animals.
From what I've read, they tend to bond to there owners very strongly. But if you got a pair and didnt getted them neutered, the male and female would both grow small tusks and the male would become quite territorial. Females can be kept as indoor pets if Neutered/spayed and I think the same go's for males.
I found some pics on a website, cant remember what it was of muntjacts living indoors.
A good exotics forum is Sybilsden, covers basicly every exotic you could think of....