any special tools required ? cant find a guide for it has anyone done it before

Hardest bit is supporting the bike, check this thread out.

viewtopic.php?f=24&t=33252

I'd say the hardest bit is getting the old inner race off the bottom yoke or the new one on without a bearing puller or presser. There are a few ways that people have done it, but since the yoke is off the bike, it was easy to just drop it off at my local bike shop and they swapped them over from free. Took about 5-10 mins.

yep.. the bottom bearing is a pain in the ass... when i took my yoke and steering stem out. the bearing actually came off the inner race.. so it was only the race that was stuck on the stem. and what i did to remove it i got a sharp center punch... placed it at the top groove on the inner race, and hammered it a few times. and the whole race cracked into two pieces and then i just pulled it out of the stem.... it may be a bit risky doing that as you MAY punch the stem by accident... ONLY do this way if its the last resort and u dont wanna pay a garage

hammer. chisel. carefully. easy.

+1

or chisel, i had no chisel so i used center punch