Are you going to make the enclosure indoors? Make it as big as possible-Malayans need both land and water-but mostly water. They are very aquatic, much more so than NA box turtles. The water should be heated if you live any place other than the tropics
They are mostly herbivorus but will like some high quality protein a few times a month. Keep two females together, not a male/female pair. Even if you intend to breed them, keep them apart except for breeding time.
I wish my book was out now! I did a lot of research on the various box turtles from Asia and also received help from some knowledgeable, long time keepers like Mary Hopson and Dr. Healther Kalb. I covered their husbandry pretty well. Email me and I'll email the chapter to you! Tess