There are 3 plugs in the engine block (2 - pass. side, 1 - drv. side). 2 plugs in each head. It is easier to replace plugs in the block from underneath (remove the oil filter before). I use a big screwdriver and hammer to get old ones out.
Remove plugs from head from under the hood (remove PS pump and alternator before) and from the insede the cabin (there is a hatch), but remove a coil before.
I used RTV with new plugs to prevent leackages.

It is easy to make new plugs. You need to find a shop with lathe. Cheap job here. I made them of stailess steel.