slimming pills, sorry nothing came up on that one on the Customs webpage, but it might be stop by customs if it requires approval from the Health Ministry.
but vitamins pills will get thru without a problem.

You can find it beside LCCT, it has the big sign MEL & KURIER with the pos malaysia logo.
1. go to guard house, pass your driving licence and they will give you a visitor pass.( you can drive in )
2. go to inside the building ask for the pos malaysia-kastam-office (pos malaysia staff)
3. go to the counter. wait for the people to entertain you while they are bz picking up calls and scribling something at the work desk.
4. once they entertain you, they will say "pickup consignment?", give your EMS tracking number and later they will ask for your IC
5. then they will ask you to sit down and wait, after they finish preparing the work paper, they will call you to the counter and pass it to you
6. you will need to go to counter 5 if im not mistaken, with the red sign number and pass the paper and your Visitor Pass to the person there, he will ask for your ic again, and collect your box and put it on the conveyour for you to collect.
7. he will ask to go to kastam inspection counter with the box and there you will be given a knife to open the box.
8. once inspected, they will say go to the next counter with the officer inside a cubical
9. the officer will ask you what item and check his/her thick book to make sure 0% tax, after that will say "oh this is high value item,no tax, need to declare"
10. you will be ask to go to the Pos-kastam-office again and tell them "Kastam minta buat declaration kerana high value -tiada tax (if there is no tax)",  they will ask you to sit down again and once ready they will call you and ask to pay for the declaration letter RM18-22( i dont remember)
11. go back to the kastam counter and give the letter.. youre almost done... officer give you back the letter with his chop and signiture..
12. after that go back to the counter where you collect your box and pass all the paper work and he will pass you back your visitor pas.
13. you can walk out with your box now towards the security stop and collect your driving licence.
14. the end.

All the time dont leave your item unattended.. if its too big just leave at the inspection counter.. ask the officer to watch over
TOTAL time "ping pong around more less 1 hour"