Cage, 
Your script as described sounds ideal for transfering a good right hand side morph target onto the left hand side( and vice versa ), unfortunately I haven't had much luck making it work. This will be entirely down to me being tired after a busy day at work I'm sure.
 
What I did was load Antonia and the shorts and set her right leg to -60 degrees then I corrected the poke through with a custom morph made with the morph tool.  I then ran your script ( the most recent one you posted here ) and selected mirror, selected the hip2, selected -ve to +ve, and selected the custom morph. I then saw a dialog box come up with a stream of 'No match  followed by coordinates. One this ended a new morph target was created on the hip2, called custom morph_1 but when I dialed this it acted on the right hand side, ie the same side as the original custom morph.

Like I said I'm sure it's something I'm doing wrong because I'm tired and not thinking clearly, but any advice on where I'm going awry would be much appreciated. Meanwhile I'm going to go get some sleep and hopefully be more alert tomorrow.

Cheers

Ian