Colonel Kadat has two old, but still useful tutorials in learning how to hack unity3d games, it's just up to you on your end to spend the 3-7 weeks perfecting and understanding how to hack this type of game, I say 3-7 weeks, because it took me about 2 months to figure most of it out, and I have been doing this stuff since May.
Kadat's YouTube Tutorials:
Contract Wars IS NOT a good game to start learning how to hack on, Wind Runner is a good game to start with, then maybe Dead Trigger 2, and when you've made hacks for both of those games, then try Contract Wars if you feel confident.
SWF/AS3 hacking knowledge would be helpful, but if you don't have any, it may prove difficult in the long run. anyway goodluck.
I'm not sure if Kadat listed the CIL Bytecodes in his tutorials, like SWF hacking, there's the AS3 bytecodes for a given function, Unity3D has the same set of stuff, so here's the CIL Definition list:
List of CIL instructions - Wikipedia, the free encyclopedia
And his SWF Memory Dumper now dumps Unity3D DLL Files so make sure you nab that as well:
He's a konghack moderator/admin so that's one way to contact him if you want to try to contact him, he's pretty short spoken and blunt and can sometimes come off as an asshole but he means well, you just gotta realize the fact that he's the fore-father of unity3d hacking and 'IS' the only guy that has made an attempt to make free tools for hacking U3D Games.
With all that said, I will not help you further, I didn't have anyone except his two tutorials and various google searching here and there to figure stuff out for myself since every U3D Hacker out there, they don't share their secrets. So finding what to modify and how to modify will be your endeavor, not to mention creating your own understanding and methods.
Goodluck!!!