When you beat the 7th gym leader and have seen everything at the lake you go to spear pillar at the top of MT. Cornet
No only in Pokemon platinum (coming in stord march 22 2009) no it is not possible to get into the reverse world in Pokemon pearl. It is is only in Pokemon platinum which comes out on march 22nd in the US
http://www.serebii.net/platinum/tornworld.shtml
You should Know that.
shadow lugia is not in Pokemon platinum
The Distortion world is only available in Pokemon Platinum
once you get so far in the game, an event similar to the ones in Pokemon Pearl and Diamond will happen, only with giratina and the Reverse world
(Pokemon Platinum Only) A portle to the Dostortion (Reverse) world.
You need to battle Girtina in the Reverse \World then you will be able to go to Sunnyshore
A portal to the reverse world,pokemon,rocks,pillars,and griseous orb in reverse world. also, there is giratina if you didnt already catch it and a rare bone
You need to fight Dialga and palkia where u fought them in dimond and pearl and then after u defeat them you get sucked into the reverse world.
pie
You don't need surf to get through the distortion world. You only need the move strength.