I think you need the following:
- activated carbon mask;
- protective glasses;
- latex gloves;
- two syringes;
- a cotton swab;
- a little brush;
- isopropyl alcohol;
- kapton tape;
- an hot plate, something like this http://uk.farnell.com/productimages/farnell/standard/401501006-30.jpg
- tin paste;
- microscope (10X at least);
- directional light for microscope;
- liquid flux;
- a wood block;
- flux cleaner.
You have to solder the device in a non conventional manner, because the classical soldering pen is completely useless in this case.
The process is quite simple, but patience and careful are essential. The entire process can take even hours, depending on the device to be soldered, and must be performed BEFORE the board component mounting.
Caution: the following procedure can be dangerous for health, so remember to wear mask, glasses and gloves from begin to the end!!!! All the following steps need to be done near an open window or under an extractor fan.
First of all, either the board and the device must be extremely well cleaned with isopropyl alcohol, because dirt and grease can compromise the job.
Fill the first syringe with the liquid flux, remove the needle from the second syringe and place the cotton swab in its back, to make it easier to manage.
Place the device on the board in the correct position, mark its position with the kapton tape and remove the device. Precision in this step is crucial, because it will make easier to hold in place the device during soldering process.
Now you can turn on the hot plate and set it to about 210 - 220°C (392 - 410°F). It will take a little, so you can work on the board. Place the board under the microscope and,with the aid of the syringe needle, spread a thin layer of tin paste on every pin to be soldered. From now unti the final washing of the board, the process is done under the microscope. Once every pad has been covered, the board can be placed on the hot plate to begin the soldering process. As soon the tin paste begins to melt, use the first syringe to apply a thin layer of liquid flux all over the pads and place the device on the board within the kapton marks. Hold and press it in place with the back of the cotton swab for about 3 seconds then remove the board from the plate and place it on the wood block to let it cool down slowly, always pressing and holding down the device with the cotton swab. After about a minute, release the pressure and wash the board while it's still warm with the flux cleaner and the little brush. Wash again the board using isopropyl alcohol and check for problems under the microscope.
If all the steps has been done correctly, you now have a completely soldered LGA package to a board.
You can now begin the normal copmponent mounting process.
Greetings from Italy,
Valentino
P.S.: I'm sorry for my poor english 
