I believe that GL_OES_texture_npot and GL_ARB_texture_non_power_of_two indicate that GL_MIRRORED_REPEAT can be used with NPOT textures. However, none of the following report this extension:

Adreno (TM) 205
GC530 core
GC860 core
NVIDIA Tegra 3
PowerVR SGX 530
PowerVR SGX 531
PowerVR SGX 540

Is it true that these do not do GL_MIRRORED_REPEAT on NPOT?
I can't imagine that NVIDIA would not support this.
Is there some other way to NPOT GL_MIRRORED_REPEAT?