shoes edition

Hi!
Do you have some tips or tutorials for edition shoes? I want to new boots but i dont have any idea how start... I have iff editor but it crashes always when i want to edit for example shoe_100_00... i also decompressed them but after that program also crashes (i found this tips in tutorial fon nba 2k9 iff editor)...
Could u help me?

try to use modtool..

i put motool in C:\Program Files\Autodesk\3ds Max Design 2010\Scripts\Startup but i doesn't work... i have 3ds max 2010