i have made wandering eyes before. If you have one layer as your main eyes, but use 'sided' eye textures, don't put the pupil in one side.
The next layer put on top should be transparent with just the eye, for the side with the blank eye.
For instance, i used this code
}
pass
{
cull_hardware none
cull_software none
alpha_rejection greater_equal 128
texture_unit
{
texture eyebase.png
}
}
pass
{
scene_blend alpha_blend
texture_unit
{
texture eyepupil.png
wave_xform scale_x sine 0.8 0.2 0 0.15
wave_xform scale_y sine 0.8 0.2 0 0.15
wave_xform scale_x sine 0.9 0.5 0 0.1
wave_xform scale_x sine 0.9 0.1 0 0.1
}
}
}
}
But you may need to rework it to suit your tastes.