When I took Tiger Airways from Manila in 2007, I bought a cheap hardcase and checked my guitar in. They pasted a fragile sticker and guitar and case came out without any scratch.
But after I check in on that flight, I saw another guy with an acoustic guitar in a very bulky Ovation hardcase. He didn't check-in his guitar and the crew allowed him to carry his guitar to the plane. He put it on the overhead compartment and I was suprised to see the whole thing fit in there.
On another time, I brought in a bass guitar. Didn't have time to look for a hardcase, so I bought 2 thick softcases, and wrapped one over the other. I put in some foam and carton to keep the neck steady, then checked that guitar in. Some scratches on the case, but the guitar went out fine. The customs officer in fact mistook it for a golf bag.
I guess, you're best bet is, buy a hardcase, then try to bring in.. If they don't allow you, then check-in.