[http://www.finetunedmac.com/forums/ubbthreads.php?ubb=showflat&Number=19500|I found a forum post that explains the connection in detail]. The connector is the same for all displays, but a higher wattage adapter is required for the 30" model. To sum up the forum post, the connector has a symmetrical pinout like this:
Pins 1,2,3,4,5
|+24.5VDC|-24.5VDC|SENSE|-24.5VDC|+24.5VDC|
|+24.5VDC|-24.5VDC|SENSE|-24.5VDC|+24.5VDC|
Pins 6,7,8,9,10