I stumbled across this .mqo import/export plugin for Mod Tool 7.5 by ze10 and thought i'd post it here since new import/export formats for Softimage are rare but always appreciated.

http://nullorempry.jimdo.com/work-list/softimage/

Old link
http://pr0jectze10.tuzigiri.com/simpleVC_20110127212021.html

You can download it from the developer's SkyDrive account HERE.

I could only read bits and pieces of the README so i'm not exactly sure what it all says.
I tested the import and export feature and it works most of the time. It doesn't seem to like importing files with binary vertex data though, for example; the cat.mqo file in the Metasequoia installation, but since the plugin is open source python you could modify it to work how you want. To export to *.mqo from Mod Tool your mesh objects need to be under a model null. If it works in Mod Tool then it'll likely work with commercial versions of Softimage also.


Local backup: