i've done this before,
1. there's no white tiger at the temple of sheung wan as it is "man mo miu"
2. you have to go to tin hau temple at tin hau
3. you can go to the market and buy Fat pork, about $2 dollars will do
4 when you arrive there, you may ask the "miu chuk" how to do, he will tell you, i remember there is one packet of burnt paper to buy etc.