This should help:
http://www.nexstarsite.com/PCControl/RS232Cable.htm
http://www.astrogeeks.com/AstroGeeks/cables/index.html
I made one for a CG5-GT. Go down to dick smith and get a db-9 serial port plug of the correct gender (usually female to plug into the serial port on your computer). Watch it- most modern computers no longer have serial ports and making all this work on USB is a whole new kettle of fish. The manual for your Nexstar will have the pinouts listed. Get a phone cable and strip the plug off the end you don't want. Note which wires on the clear phone cable end are the ones you need. Solder them to the pins on your Serial plug (DB9) as specified in your nexstar manual.
For me, the DB9 plastic housing didn't hold the cable firmly enough and since there are only two thin wires soldered to the pins I decided to fill the plug with liquid nails.
Of course, you might not have soldering iron, liquid nails etc.
EDIT: I'm actually in Perth not Singapore so not quite so far from you after all! I go out to Bakers Hill for the ASWA deep sky viewing night almost every month so if mine is the same as for the Nexstar you could have it and I'll just make another. If you can send me the pinouts of your nexstar I'll compare it with my CG5-GT. I'll bet the skies are nice and dark where you are!!