mktong,
to fly in msia you will definately need to convert your licence into malaysia cpl/ir. on that issue, you will need to contact malaysia dca. from what i gather, they can be quite tough with faa guys. no idea why.
once you have successfully converted your licence, then i would suggest either mas or airasia. i would believe airasia will be easier as mas, though short of copilots, tend to be selective but no harm giving it a shot.
no doubt needs $$$ for conversion. currently, the only flying school i know of in msia is mfa in malacca. heard there's another one in langkawi or ipoh but i'm not sure. dca malaysia will be able to provide you with the answer.
good luck.
SR