Finally got it! Under Sharp ROM 1.32 with special kernel, I installed libSDL_1.2.6cvs-1_arm.ipk, zlib_1.1.4-2_arm.ipk, visualboyadvance_1.7-SDL-1_arm.ipk, and snes9x_SDL-1_arm.ipk. Snes9x runs very smooth with sound. But the landscape view is a bit annoying. VBA is also playable with sound off. I tried to set the sound sampling rate to 11khz. It sounds better but still not satisfactory.
Cheers!