Yes it can be done, but will require you to get a few things.
Automatic Climate Head Unit
LS dash wire harness or cut the connectors you need.
Mode Control Motor - behind radio area on drivers side of the evap housing.
Heater Core Temp Sensor - bottom on evap housing under heater core.
Outside Air Temp Sensor - Unger hood latch area.
Max Cool Motor - attached to air meix control motor, same harness as HCTS
Sunlight Sensor - Top center of dash between defrost vents
The sunlight sensor should have a tinted plastic cover. I don't know what happend to this one.
All you need to do now is get a wiring diagram of the Automatic Climate Control and start putting it together. You will need to use a drimmel to cut out the piece of plastic where the heater core temp sensor goes. On an L model it is covered up. You will need the connector off the harness side of the Mode Control Motor. You will also need the main harness connector that goes to the climate control unit. You will also need the harness that plugs in to the max cool motor. The outside temp sensor is prewired on all Legends so just attach the sensor plug in the harness. The other end of that harness is not attached so you will need to look around the passenger side interior kick panel area for that wire. They are pink and black if i'm not mistaken. I think thats about it. Have fun splicing wires, there will be alot of that.