Try to find the right tool. A screwdriver can be used if the bolt doesn't have to be tightened very firmly but you need the correct tool to do it right. Torx bits are now common and you should be able to find them in Malaysia also.

As jimc101 mentioned Torx bolts are appearing on more and more bike parts. The chainring bolts on my new Shimano 105 crank (FC-5700) require a T30 bit so their use is increasing.