its really easy......i got it from some forum. u just keep using the following
chords.....i dont kno the names but check out the strumming pattern through the
song. 

   |--3------3------3------3-----------------|
   |--3------3------3------3-----------------|
   |--0------0------0------2-----------------|  
   |--0------2------2------0-----------------|  
   |--2------3------2------0-----------------|
   |--3------X------0------X-----------------|
       G     G1     G2     G3 <------- i dont kno the real names

 (strumming starts from the middle of the song)

  G               
ke main hoon jawan 
         G1
O maray dil main hai aag 
    G2    
Ab koi nahin saath
     G3
Hai kali yeh raat 
     G
Mere sar peh junoon 
        G1
meree ankhon main khoon
        G2
mujhay aayee naa sakoon
       G3           G
par main naa rukoon ga

ends with G. 

(NOTE: the guitar tuning in that song is two frets up-higher)