Use the MAL to find the treasure. Keep in mind the following:
The treasure is found in a random location (anywhere in the zone). If you're in a group, each person will be heading to different treasure locations.
The MAL gives you two basic readings: Directional Color and Distance Strength
Directional Color:
Red = directly behind you
Orange = somewhere behind you
Yellow = somewhere in front of you
Green = straight in front of you
Distance Strength (in order from far to near):
Faint, Dim, Dull, Bright, Blinding
When you're standing right on top of the treasure the MAL will glow with a blinding greenish hue. At this point use the MPMDD to dig up the treasure.
Sometimes even a single step in a different direction can change how the MAL glows. If you think you're really close to the treasure and then suddenly seem to be far away, try stepping backwards a number of steps and use the MAL again. It takes a little bit of tweaking to find the treasure.
A discussion page exists which may contain more information