Can't you use dderidex's SFC3 Util5 for that?
You can use a hex editor to chagne the hardpoints, but it's damn hard. Open the .mod file open in a hex editor, and you should see some tag and then a whole loads of coords.
Assimview can edit sfc hardpoints and you can get it from assimsoft.com. Read the docs because its a huge confusing program.
Alternatively my improved milkshape plugins will be out soon that will be able to do it.
DDeridex's SFC3 util lets you change hardpoints.