Use gcc 4.2 in Xcode 4.2 and iOS SDK 5.0

I just upgraded to Xcode 4.2 and iOS SDK 5 earlier today. But everything seems different with new compilers.

There are two "Compiler for C/C++/Objective-C" options now, "Apple LLVM compiler 3.0" and "LLVM GCC 4.2". GCC 4.2 is missing.

Apple LLVM compiler 3.0, builds really fast(I like that), gives me 999+ warnings, and my game can no longer run. It looks like there's some differences on memory, and it crashes when loading our game's scripts.

LLVM GCC 4.2 is so god damn slow, I still cannot finish one build after hours on my i7 machine.

And, one more thing is our engine uses gcc command lines to build(instead of xcode).

So, it leads to one question, how can I use gcc 4.2 in Xcode 4.2? Is that even possible?