Hi everyone,
I tried to do what Alblaka said in his earlier post but it didn't work.
So I merged the two conflicting classes (ItemPickaxe and World).
To use this simply drop the files in your minecraft_server.jar after you installed both Industrial Craft 8.55_02 and Mineforge 1.0.4
Here are the two merged .class files (ah and dj) Click Here!
Alblaka, if you don't aprove of this, remove the link and send me a PM, I'll take the file offline.
-- trilader
Warning: Make a backup of your world before you use this... For me it caused a bug with the old BuildCraft (1.7.3.4) that corrupted the world. Fortunatly I had a backup.