How do I UNLOCK modded SGC files from Richard Burns Rally?

[squidiskool]

I'm not tryin to hurt the community, I'm just looking a way to crack this locked file. It's the SGC file from Richard Burns Rally. 

I can import stock car models into Zmodeler 2, but when I try to import mods it says
This file is locked and can not be imported
How do I unlock it?
I am NOT trying to steal someone's hard work model. I'm just wondering how to unlock it.

sample: PLEASE DO NOT USE THIS SAMPLE FOR STEALING.
http://www.mediafire.com/file/szz28bg0oc...4.sgc/file