I also used a 48W temp controlled unit for it. Took about 10 min for me. But i solder a lot so i have a lot of practice in the fingers. The trick is getting a little solder on the pad and keeping the heat up. Wish is not easy with the aluplate transfering the heat away. In my case i used a heatgun to help with that. I just made a simple contraption to hold the plate laying the heatgun on the table and aiming it on the backside of the plate and then soldering on the other. PS keep distance between heatgun and plate. Not to close!
// Marlark