To unlock the samsung galaxy S, Follow the instruction below. (try this at your own risk)

1. Install this apps called "SGS Unlockwhich can be found in the android market on your phone.

2. Open the SGS Unlock apps and copy (write down) the unlock code and the unfreeze code.

3. Watch the video below and follow all of his instructions carefully. [While working on your phone, you might get an extra code called "mcc/mnc lock". This guy however only had two of them (unlock code and the unfreeze code). Refer the video on the 6th min and 11 sec. This mmc/mnc code shall be use if you want to lock your phone again.]

All the stuff that you need to download as seen in this video (only one software) should be available on the link from this page.  Unfortunately you have to register before you can download it.

It should be work and if you want to lock it again, just follow this instruction from the same forum. Read the 3rd step section.

It worked well for my phone and I already tried to use maxis simcard from Malaysia. :)
Alhamdulillah, so after this i don't have to worry to need to call Meteor again and ask them to unlock the phone for me. :)

Thank to xda developers forum for the great work. ^___^
Should anything bad happen or anything did not work, i hold no responsibility at all. 
Again, try this at your own risk!
I just share this information because it works well for me. For a detail explanation, refer to the link attached.