This tutorial uses the new skin wrap modifier in 3DS max 7 to enable the mirroring of morph targets. Ordinarily, if you sculpt a one sided target, raising the left side of the mouth into a smile for instance, and then mirror that shape you would expect it to give you a right sided smile target. Not so! In fact, the effect of blending the right smile to 100% will be exactly the same as blending the left smile to 100%.
To effectively make a mirrored morph target, mirror your left target naming it rightTarget and hide the left target. You should now have a mesh that looks correct (though it won't work as we've just found out).
Make a copy of your base mesh, making sure all the morpher targets are set to values of zero, and collapse it to an editable poly. Name it baseCopy_01 and Hide your base mesh
Add a morpher modifier to rightTarget and load baseCopy_01 into channel 1.
Crank it up to 100. This should blend your rightTarget mesh back so it looks identical to the baseCopy_01.
Now make a copy of baseCopy_01, name it baseCopy_02 and hide baseCopy_01. BaseCopy_02 will actually be the mirrored target.
Move to frame 10, turn on autokey and return rightTarget's morpher channel 1 to zero. Turn off Auto Key.