is it working in multiplayer

Yes you just need to put the file you create when using the program in a new / your folder ...

can anyone see it in multiplayer??

nope, if you want people to see them in multiplayer you have to buy them.

I don't understand the part where you click on generateitem.dat o.e please tell me what to do next ..

Well, you can see yourself with dat colors,but no one can see the colors you are using, you need buy.

Also: don't worked with me in 4.2 version.

Hmm how can i use it?

is it for mac? if so add me on skype and tell me because i dot go on heremuch im vancecraft

lol good thing i know wushu :

i dont understand how to do it can u help me?