I would have to disagree, technically it is unlikely to be legal as you are breaking both the license agreement which came with the cider game you extracted the wrapper from and the PC copy of of the game you are ciderising. Re-engineering and then running the software on hardware it was not licensed is at best a grey area and at worst is definitely illegal. Here is just one part of the copyright notice on Borderlands PC for example.
"You agree not to...
Reverse Engineer, decompile or dis-assemble, prepare derivative works based on or otherwise modify the software."
Taking the game exe then using reverse engineered DLL files and other technology from a second game (which likely has the same agreements) to create a hybrid binary that runs on the Mac definitely breaches the user license agreements. US copyright act states you can have penalties of $150,000 per violation!
There are at least a few more similar points that are likely breached when using anything on the porting team website. If you want to be stay legal according to copyright law then I would not use any porting team ports as they are a grey area at very best.
I know my career means people not paying for games and using the porting team effects me so I will have some bias however regardless of the sides you are taking in this debate I would not want to tell anyone this is definitely legal.
Edwin
There was just a huge case in Norway about End user license agreements here in Norway five years ago. (It was when apple introduced iTunes). There was also the cases with DVD-Jon, which won all the cases against him, because he owned the software and was protected by our national laws, which a company must abide if they want to do business here.
If you are selling something in Norway, you have to comply with national laws and EULA was deemed "a non-binding contract" in court.
http://www.pcworld.com/article/108462/defendant_acquitted_in_dvd_hacking_case.html
Jon Lech Johansen, also known as DVD Jon, has been acquitted in Oslo City Court of charges over his development and distribution of DeCSS, a program that can be used to break the digital copy-protection mechanism of DVDs, his attorney said Tuesday.
The court found that Johansen was entitled to access information on a DVD that he had purchased, and was therefore entitled to use his program to break the code, attorney Halvor Manshaus said Tuesday.
I could only find the Norwegian version of the full story.
Don't get me wrong, I do not pirate games! And I never will!
And I'm a huge fan of those who actually take their time to release their games on the mac platform and if it's available a Mac version of the game, I'll always buy it! Unless there was no announcements about a mac port being released.
As far as i know, all legal inquiries agains wine and codeweavers has so far been dismissed.
I do own several cider based games, like Dragon Age:O and 2.
Thus I can legally put my contents from another game into the cider build i've already payed for.
Maybe it's illegal in USA, but it is not even in the grey zone here.