Additional information would be very helpful in trying to help you out -- what is the error message, how are you proceeding and at what point exactly things go wrong.
No other 'installation' is needed.
thank you buddy even i am trying to do this but getting wrong some where..i will try this out..
but in their site they specified that first we have to plugin then rake it, it will copy relevant .js files into scripts folder,we have one more option of downloading and installing prototype.js file supplied by them... i dont know how to work with prototype.js
thank you in advance