I'd pick up a SilkAir flight to somewhere you mention. It's relatively cheap (though only top fare classes will earn miles, and then only on KrisFlyer not MP). You don't have to go to CGK--there are lots of direct flights from SIN to various Indonesian destinations which are a lot more fun. Or try Kuching or Kota Kinabalu and you can go from there direct to KUL, if that's where you have to be in the end.

(KUL isn't that interesting either...good for a day or two but not a ton to see)